How to exclude resource cost contribution to co-products | GMF

Hi All,

We are looking solution for the following specific requirement and our cost method is PMAC.

In our implementation, Formula has primary product (with actual qty) and co-products (with 0 qty). After yield, based on quality results primary and co-products are get certified. As per cost allocation factor, RM, PM and Resource costs are distributed to each products certified.

But, requirement is all the costs (100%) should go if primary certified. If primary and secondary products are certified, then only RM & PM cost has to go to co-product, not the resource cost.

How to achieve this functionality through OPM?

Contribute to Yield function available only for materials in Formula. Anyway to restrict in resource function?