Is it possible that a project responsible inherits his project rights on project sub-objects?
Your help would be greatly appreciated!
No, not quite how you are describing.
BUT, if you give your users permissions on the sub-object GLOBALLY, because the only projects that they should be able to view are ones that they already have rights to, then this implies that they only get the (global) right on specific projects.
You need to think about whether this works for your use-case though