Hi William,
sometimes it's good to bring something up again The IP is defined by the source system. If you develop on the partner tenant and deploy the solution to the customer test tenant, the Intelectual Property is at you, because you have the original solution.
If you start your development on the customer test tenant, the IP is with the customer.
But this is only the legal situation (disclaimer: no guarantee, I'm not from the legal department).
The byd/c4c system supports multiple partners. This means when your user is assinged to your partner, you can only see solutions that got created with your partner ID (you or a colleague of you).
If someone with another partner ID logs on, he would not see your solution. So each partner can only see his own solutions.
I'm not exactly sure how this user to partner ID assignment is done. I'll try to find more details on this.
I'm more familiar with the C4C world, where the partner ID is the customer ID and all developments are starting on the customer tenant. There of course every partner can see the solutions. But this is okay as the IP is with the customer and the customer often wants to have multiple partners working on one AddOn.
Best Regards,
Stefan