A key idea with the supply chain economy as discussed in the past is that a product put up for sale can include parts from other designers and that payment for a product would flow to all participating designers. I think it would be wise to create a psuedo-product that can be include that might be called a "resale license". Pure information. No 3D model, no script, no nothing else.
The purpose would be to make it so partners can get paid their cuts, sometimes for contributions that won't be on any specific assets inside the product. Let's say, for example, that someone wants to license the use of a brand name in a third party product. That designer agrees to pay S$X per unit sold.
One thing that would be super helpful, whether this gets included or not, will be the ability for someone viewing a store item to see all the contributors to the product. That would include for these resale licenses. This would be a good way for people to verify that partners are abiding by the terms of their licenses. It might be worthwhile for a "license item" to have a short public statement indicating the terms of the license that anyone could examine.