Why not work on the relationship(s) first, and then find a configuration that works for all of you, as opposed to shoehorning your potential relationship(s) into a predetermined configuration?
Mono. Divorced, two kids (DanceGirl, 14; and PokéGirl, 12), two cats, one house, many projects.
My partner. Poly. In relationships with me, Xena, and Noa.
Poly. In a relationship with Chops. Dating others.
Married, Poly. In a relationship with Chops.
External blog with a mono/poly focus: From Baltic to Boardwalk