We are trying to update revenue splits using SOAP API from external system. We have a sync running between Opportunity to another record in external system. When the data gets updated in external system we need to update the opportunity revenue splits in salesforce but we are getting errors because Salesforce has a validation on the Revenue splits that the total of their contributions should be 100%. Consider a scenario that there are two Revenue splits on the opportunity where Opportunity Owner being 70% and other user being 30% and this data gets reflected to the external system. Lets say they remove the other user with 30% contribution and add another user for same contribution in the external system and we need to sync this data to Opportunity. We cant use upsert here since it would be 130% contribution on SF side and it would throw an error. So, basically how do update splits satisfying 100% contribution criteria. 

We are trying to update revenue splits using SOAP API from external system. We have a sync running between Opportunity to another record in external system. When the data gets updated in external system we need to update the opportunity revenue splits in salesforce but we are getting errors because Salesforce has a validation on the Revenue splits that the total of their contributions should be 100%. Consider a scenario that there are two Revenue splits on the opportunity where Opportunity Owner being 70% and other user being 30% and this data gets reflected to the external system. Lets say they remove the other user with 30% contribution and add another user for same contribution in the external system and we need to sync this data to Opportunity. We cant use upsert here since it would be 130% contribution on SF side and it would throw an error. So, basically how do update splits satisfying 100% contribution criteria.