Asset Accounting and Sponsored class derivation

Hi:

In FI-AA we have around 10 asset classes, on sponsored project our client receives budget for various items falling in one asset class. E.g in computer and accessories , he might receive budget for Tablet ,Laptop and Desktop PC separately hence they need to record their budget and report them separately. Sponsored classes have been created for them. Now when it comes to derivation , i am confused how will i be deriving sponsored class for a same asset class. In FM-BCS i was using FMDT_READ_MD_ASSET to map asset class field to USERTEMP1 and hence setting a derivation based on USERTEMP1 (asset class) and Cost center to derive Fund center and commitment items. When it comes GM i can not use this criteria because of multiple sponsored classes falling in an asset class for a sponsored project. Please share your experience of deriving sponsored class when creating asset master.

Regards