I am trying to perform an Upsert Operation from SoapUI using enterprise WSDL. For a single object it is working fine. The actual problem is comming when i am trying to perform this operation on 2 different objects. Its giving me the error that only one sObject type is allowed. For Example let's say that i have an Account and a custom child object Payer. So now i want to perform an Upsert on both the object in a single API call. If any of you can provide me a SOAP call example for this scenario it will be of great help. 

Thanks in Advance!

I have created a checkbox SendToSAP on account, which should be 'true' when a record gets created or every time it gets updated. I have set the default value of flag to true and written a trigger on account to set it to true after update.
But the problem is when i am trying to make this flag 'false' through my apex code the trigger is again setting it back to true. so i am unable to set my flag to 'false' in any case.
Can anyone suggest me the workarround for this problem.

Thanks in Advance!