CJ88 User Exit for COPA Settlement

[AK37]

Dear Expert, 

I am facing an issue with CJ88 settlement to PSG. 

I have a COPA Account Based and I know that the characteristics reported in COPA Line Items are the ones reported in WBS Settlement rules filled in the WBS Master Data, but I want to add a characteristics (Material Group) based on Product reported in the ACDOCA line item that I am settling.

I have tried to see COPA Enhancements, in order to derive the material group, but they are not useful because they works on characteristics already filled and the Product is not in these one. 

Any suggestion how to works? Maybe a CJ88 User Exit?

Thanks

Armando