Eugene:
I have no advice, but am thrilled to see you asking this question and the background information you bring along with it. Of course, there are similar problems with the Stewarts, the Bruces, the Fitzalans, Fitzwalters, etc.
This is a great place and time to be discussing and deciding these matters as we are beginning to prune down the number of duplicates....
My hope is that several of you with some depth of background and resources on the topic will lead us to a clear and workable solution to untying this Celtic knot!