While your scenario is a challenge to follow, what may help immediately is that only 'Primary' PCs need a license, Secondary PCs do not.
If you need to control another Primary with a Primary, that one Primary must be demoted to a Secondary 1st. You can do this and still keep the activation on the Primary - you will be prompted if you want to deactivate it and you would say 'no'.
Lastly, activation and the status of Multiplicity as a Primary or Secondary is on a PC basis, not a user one; meaning, if it's a Primary on 1 Windows account, it's a Primary for all Windows accounts on that same PC.
Sean Drohan
Stardock Product Lifecycle Manager