Restrict or warn assigning a Team Member as assistant if they lack the Team Lead's work skill

Requirement

We use the Assisting Activity / teamwork feature, where a Team Member (field resource) is added as an assistant to a Team Lead. We want to restrict, or at least warn, when someone tries to assign a resource as an assistant to a Team Lead if that resource does not have the work skill(s) the Team Lead has.

Today, any resource can be added as an assistant regardless of work skill match, which means a helper without the required skill can end up assisting on an activity they aren't qualified for.

We would like a standard, supported way to either block this assignment or show a warning at the point the assistant is added.