How to Consider open past sales order in IBP for Supply as a demand

Hi,

We are in S&OP 3.0.2.2 (On premise Customer) and implemeting IBP for Supply. As of now we are using standard CONSENSUSDEMAND key figure to pass forecast as an input to Supply Planning engine.

Our Customer also wants to consider past open sales order as an demand input to Supply Planning engine.

We don't see any standard Key figure for this. Please let me know if this is possible in S&OP 3.0 version, if yes then how?

Thanks

Girish