Nethergirl, I second that. It seems that a couple who wants a playmate would not really see her as equal because they already have a bit of territory... Whether or not a monogamous couple thinks so, there is territory. I would be interested to know (as a pan sexual myself) if you guys (the couple) are truly poly as individuals or if you decided as a couple that you want to safely add someone so you can be there to make sure the connection with desired HBB doesn't make you jealous.
I only post with good intentions as I am curious about your pursuit.