I would like to use a protect rule based on whether an object is part of a peer reference. Here's the idea which doesn't work:
IF Customer NOT(IN LoggedInManager.Customers) THEN READ PROTECT Customer From Manager
You get the idea. In the above, Customers (plural) is the reference attribute to Customer. Peer relationship with many. So I'm looking for a way to determine whether the two objects have been related. Seems simple. Doesn't seem I can use NOT and IN together in any way.