User Exits or BADI's or Any Function Modules in FM-BCS

Hi,

We are having requirement like, system to check the budget from different account assignments which are not given in the transacation level.

and consume the budget in Account Assignments which are given in transaction.

Using the 110 Payment Budget.

Eg:

1. Consumption Budget ( Used for Procurements )  is Uploaded is F1+FC1+CI1 - 10000 $

2. Consumsption Budget ( Used for Consumptions ) is Uploaded is F1+FC1 +CI2 - 5000 $

If reservation is Created for 6000 $ for Account Assignemnts F1+FC1 +CI1,Then System should go and check the Available budget in F1+FC1 +CI2 if budget is not there error.

if budget is there and do actual posting in F1+FC1 +CI1,means 10000 $ - 6000 $ ( 4000 $ is for next Purchase if for 5000$ Created error for 1000 $ )

Like it should check the minimum value either from F1+FC1 +CI2 OR F1+FC1 +CI1 and do the posting in F1+FC1 +CI1.

Can anybody help me on this Please....We can address this with any enhancements...

Thanks in Advance.....

SAM...