I have very similar situation. It would be great if there is a CBSub plugin for this. Please let me know if there is any alternative solutions. Much appreciated!
I have to admit I was surprised by this limitation. Your wise separation of the 'payment' and the 'subscriber' led me to believe that I would find this functionality. I have 1, 2, 3 & 5 person memberships which I'll maintain by hand. I hope this arrives in the future. Cheers!