Cross Charge enabled Project PR Approval to be based on project owner of each entity

Dear Experts,

we we have a requirement to route a cross charge project PR to that entity specific project specific owner/responsible person in the entity to approve all purchases in that entity.

Example: Say, we created a cross charge project in one OU1 and it will be accessible for all other OU2,OU3..., (the project created OU1 and other two OUs falls under same BG). Now, the PRs created from different OUs (Ou2, Ou3)  to be routed to different project ownera belongs to different Ou2,Ou3.

Since he this project owners are different for botH OUs, we can assign them in key memebers with project owner role. But how to identity and route a pr from Ou2 to Ou2 owner but not ou3 owner?