Partner Royalties by Item

Customer sells software.  Sales transaction can include line items for Software A, Software B, Software C, etc.  Each line item can have a separate partner who is due a royalty payment, and that partner gets 100% of the royalty due.

So on invoice 123 for $3,000, Software A sells for $1,000 and Partner A gets a 10% royalty for Software A, Software B sells for $1,000 and Partner B gets a 15% royalty for Software B, and Software C sells for $1,000 and Partner C gets a 20% royalty for Software C.  I need Partner A to get $100, Partner B to get $150 and Partner C to get $200.

Currently I can configure NS to have multiple partners receive royalties, but the contribution of all the partners in the aggregate must equal 100%.  The royalties are totally wrong if I put each partner contributing approximately 33.33% so the contribution total is 100%.  Does anyone else have a similar situation and if so, any suggestions for a workaround?  I am afraid inc comp is not designed to handle this scenario in which case I need to find a way to generate a cash collected report in NS since royalties are paid on collections by item.  I would SOOO rather someone