Security for Project to just allow identities of the relationship of the "Project Team" to see/edit

I have looked into MAC and DAC and basic identity based securities and cannot figure out a solution for this.

What I am  trying to do is to only allow identities that are on the "Project Team" of the out of the box relationship to project to read/write. Now this is different than a normal "Team" again because it is just a relationship to project that is identities.

Any help is appreciated, thank you!