I want to insert Multiple parent and child (Account and contacts) in Salesforce lightning. One parent and child set, multiple children if required.
Parent component :
 

<!--Parent-->
<aura:component controller="AuraSampleController" Implements="flexipage:availableForRecordHome,force:hasRecordId">
    <!--Init handler which is call doInit js function on component Load--> 
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>

    <!--Event handler for Add and Delete Row Event which is execute from Child Component-->   
    <aura:handler name="DeleteRowEvent" event="c:DeleteRowEvent" action="{!c.removeDeletedRow}"/>
    <aura:handler name="AddRowEvent" event="c:AddRowEvent" action="{!c.addRow}"/>

    <!--Aura Attribute for store Account Object List as Array-->   
    <aura:attribute name="AccountList" type="Account[]"/> 

    <!--Header Part-->       
    <div class="slds-page-header">
        <h1 class="slds-page-header__title">Create Multiple Accounts and contacts in Lightning</h1>
    </div>

    <!--Table Part-->          
    <table class="slds-table slds-table_bordered slds-table_cell-buffer"> 
        <thead>
            <tr class="slds-text-title_caps">
                <th scope="col">
                    <div class="slds-truncate">#</div>
                </th>
                <th scope="col">
                    <div class="slds-truncate" title="Account Name">Account Name</div>
                </th>
                <th scope="col">
                    <div class="slds-truncate" title="Account Number">Account Number</div>
                </th>
                <th scope="col">
                    <div class="slds-truncate" title="Phone">Phone</div>
                </th>
                 <th scope="col">
                    <div class="slds-truncate" title="Action">Action</div>
                </th>
            </tr>           
        </thead>   
        <tbody>
            <!--Iterate the child Component for display Table rows 
               with pass the List Item Index for track the Every child Component 
               and pass each List Account Instance -->        
            <aura:iteration items="{!v.AccountList}" var="item" indexVar="index">
                <c:Child AccountInstance="{!item}" rowIndex="{!index}" />
            </aura:iteration>
        </tbody>
    </table>
    <br/>
    <!--Save Button which is call Save js function on click -->
    <button class="slds-button slds-button_brand"  onclick="{!c.Save}">Save</button>
</aura:component>

parent controller :

({  
    // function call on component Load
    doInit: function(component, event, helper) {
        // create a Default RowItem [Account Instance] on first time Component Load
        // by call this helper function  
        helper.createObjectData(component, event);
    },

    // function for save the Records 
    Save: function(component, event, helper) {
        // first call the helper function in if block which will return true or false.
        // this helper function check the "Account Name" will not be blank on each row.
        if (helper.validate(component, event)) {
            // call the apex class method for save the Account List
            // with pass the contact List attribute to method param.  
            var action = component.get("c.SaveAccounts");
            action.setParams({
                "accList": component.get("v.AccountList")
            });
            // set call back 
            action.setCallback(this, function(response) {
                var state = response.getState();
                if (state === "SUCCESS") {
                    // if response if success then reset the 'AccountList' Attribute 
                    // and call the common helper method for create a default Object Data to Account List 
                    component.set("v.AccountList", []);
                    helper.createObjectData(component, event);
                    alert('Account records saved successfully');
                }
            });
            // enqueue the server side action  
            $A.enqueueAction(action);
        }
    },

    // function for create new object Row in Contact List 
    addRow: function(component, event, helper) {
        // call the comman "createObjectData" helper method for add new Object Row to List  
        helper.createObjectData(component, event);
    },

    // function for delete the row 
    removeDeletedRow: function(component, event, helper) {
        //get the selected row Index for delete, from Lightning Event Attribute  
        var index = event.getParam("indexVar");
        //get the all List (AccountList attribute) and remove the Object Element Using splice method    
        var AllRowsList = component.get("v.AccountList");
        AllRowsList.splice(index, 1);
        //set the AccountList after remove selected row element  
        component.set("v.AccountList", AllRowsList);
    },
})

Parent Helper :
 

({
    createObjectData: function(component, event) {
        //get the AccountList from component and add(push) New Object to List  
        var RowItemList1 = component.get("v.AccountList");
        RowItemList1.push({
            'sobjectType': 'Account',
            'Name': '',
            'AccountNumber': '',
            'Phone': ''
        });
        // set the updated list to attribute (AccountList) again    
        component.set("v.AccountList", RowItemList1);
    },
    //helper function for check if Account Name is not null/blank on save  
    validate: function(component, event) {
        var isValid = true;
        var allAccountRows = component.get("v.AccountList");
        for (var indexVar = 0; indexVar < allAccountRows.length; indexVar++) {
            if (allAccountRows[indexVar].Name == '') {
                isValid = false;
                alert('Account Name Cannot be blank on row number ' + (indexVar + 1));
            }
        }
        return isValid;
    },
})

Child Component :
 

<!-- Register 2 Lightning Event for handle add or Delete rows on Parent Component  -->
<aura:registerEvent name="DeleteRowEvent" type="c:DeleteRowEvent"/> 
<aura:registerEvent name="AddRowEvent" type="c:AddRowEvent"/> 

<!-- Table Row -->  
<tr class="slds-text-title_caps">
    <td> 
        {!v.rowIndex + 1}
    </td>
    <td>
        <ui:inputText class="slds-input" value="{!v.AccountInstance.Name}"/>
    </td>
    <td>
        <ui:inputText class="slds-input" value="{!v.AccountInstance.AccountNumber}"/>
    </td>
    <td>
        <ui:inputPhone class="slds-input" value="{!v.AccountInstance.Phone}"/>
    </td>
    <td>
        <!-- conditionally Display Add or Delete Icons, if rowIndex is 0 then show add row Icon else show delete Icon-->
        <aura:if isTrue="{!v.rowIndex == 0}">
            <a onclick="{!c.addRow}">
                <lightning:icon iconName="utility:add" class="slds-icon slds-icon_small" size="small" alternativeText="Add"/>
                <span class="slds-assistive-text">Add</span>
            </a>    
            <aura:set attribute="else">
                <a onclick="{!c.deleteRow}">
                    <lightning:icon variant="error" iconName="utility:delete" class="slds-icon slds-icon_small" size="small" alternativeText="Delete"/>
                    <span class="slds-assistive-text">Delete</span>
                </a>
            </aura:set> 
        </aura:if>
    </td>
</tr>
    <br/>




    <table class="slds-table slds-table_bordered slds-table_cell-buffer"> 
    <thead>
        <tr class="slds-text-title_caps">
             <th scope="col">
                <div class="slds-truncate" title="No">S.NO</div>
            </th>
             <th scope="col">
                <div class="slds-truncate" title="First Name">Contact Name</div>
            </th>
               <th scope="col">
                <div class="slds-truncate" title="Action">Action</div>
            </th>
            </tr>         
    </thead>   
    <tbody>
        <!--Iterate the child Component for display Table rows 
           with pass the List Item Index for track the Every child Component 
           and pass each List Account Instance -->        
        <aura:iteration items="{!v.ContactList}" var="item" indexVar="index">
            <c:Contact ContactInstance="{!item}"  rowIndex="{!index}"/>
        </aura:iteration>    
    </tbody>
</table>

child js :
 

({
        // function call on component Load
    doInit: function(component, event, helper) {
        // create a Default RowItem [contact Instance] on first time Component Load
        // by call this helper function  
        helper.createObjectData1(component, event);
    },

    addRow : function(component, event, helper){
        //Execute the AddRowEvent Lightning Event 
        component.getEvent("AddRowEvent").fire();     
    },

    deleteRow : function(component, event, helper){
        //Execute the DeleteRowEvent Lightning Event and pass the deleted Row Index to Event attribute
        component.getEvent("DeleteRowEvent").setParams({"indexVar" : component.get("v.rowIndex") }).fire();
    },

      // function for create new object Row in Contact List 
    addingRow: function(component, event, helper) {
        // call the comman "createObjectData" helper method for add new Object Row to List  
        helper.createObjectData1(component, event);
    },

    // function for delete the row 
    removeDeletedRow: function(component, event, helper) {
        //get the selected row Index for delete, from Lightning Event Attribute  
        var index = event.getParam("indexVar");
        //get the all List (ContactList attribute) and remove the Object Element Using splice method    
        var AllRowsList = component.get("v.ContactList");
        AllRowsList.splice(index, 1);
        //set the ContactList after remove selected row element  
        component.set("v.ContactList", AllRowsList);
    }
})

child helper :
 

({
    createObjectData1: function(component, event) {
        //get the ContactList from component and add(push) New Object to List  
        var RowItemList = component.get("v.ContactList");
        RowItemList.push({
            'sobjectType': 'Contact',
            'FirstName': ''
        });
        // set the updated list to attribute (ContactList) again    
        component.set("v.ContactList", RowItemList);
    },
    //helper function for check if Contact Name is not null/blank on save  
    validate: function(component, event) {
        var isValid = true;
        var allContactRows = component.get("v.ContactList");
        for (var indexVar = 0; indexVar < allContactRows.length; indexVar++) {
            if (allContactRows[indexVar].FirstName == '') {
                isValid = false;
                alert('Contact Name Cannot be blank on row number ' + (indexVar + 1));
            }
        }
        return isValid;
    },
})

Contact Component :
 

<!--Child-->
<aura:component >    
    <!--Attribute for store single Contact object instance-->
    <aura:attribute name="ContactInstance" type="Contact"/>
    <!--Attribute for store Index of Particular Instance -->
    <aura:attribute name="rowIndex" type="String"/>

    <!-- Register 2 Lightning Event for handle add or Delete rows on Parent Component  -->
    <aura:registerEvent name="DeleteRowEvent" type="c:DeleteRowEvent"/> 
    <aura:registerEvent name="AddRowEvent" type="c:AddRowEvent"/> 

    <!-- Table Row -->  
    <tr class="slds-text-title_caps">
        <td> 
            {!v.rowIndex + 1}
        </td>
        <td>
            <ui:inputText class="slds-input" value="{!v.ContactInstance.FirstName}"/>
        </td>
        <td>
            <!-- conditionally Display Add or Delete Icons, if rowIndex is 0 then show add row Icon else show delete Icon-->
            <aura:if isTrue="{!v.rowIndex == 0}">
                <a onclick="{!c.addRow}">
                    <lightning:icon iconName="utility:add" class="slds-icon slds-icon_small" size="small" alternativeText="Add"/>
                    <span class="slds-assistive-text">Add</span>
                </a>    
                <aura:set attribute="else">
                    <a onclick="{!c.deleteRow}">
                        <lightning:icon variant="error" iconName="utility:delete" class="slds-icon slds-icon_small" size="small" alternativeText="Delete"/>
                        <span class="slds-assistive-text">Delete</span>
                    </a>
                </aura:set> 
            </aura:if>
        </td> 
    </tr>

</aura:component>

Contact Controller :
 

({
addRow : function(component, event, helper){
        //Execute the AddRowEvent Lightning Event 
        component.getEvent("AddRowEvent").fire();     
    },

    deleteRow : function(component, event, helper){
        //Execute the DeleteRowEvent Lightning Event and pass the deleted Row Index to Event attribute
        component.getEvent("DeleteRowEvent").setParams({"indexVar" : component.get("v.rowIndex") }).fire();
    }

 })

When I click on iteration add button.The iteration is happening for parent and child.By using this code you can see two add button in both parent and child . when i clik on child add.It is adding parent as well.I want to add child when i click on child button.I want to parent and child set when i click on parent button.