Now, I don't think that I would be comfortable right off the bat witnessing them being as physical with a brand-new girlfriend that I wasn't friends with yet...but I would expect to be working toward that if the idea was to include her in our co-habitating poly family (not necessarily in a relationship with more than one of us but a day-to-day full-on full-time cohabitating famly member). If she would want to have a "separate" relationship with either of them (i.e. everyone knows about everyone but metamours having only a cordial acquaintance level of involvement) that would also be fine but I would expect the PDA in my house to approximate what they would do in public (and would modify my PDA with both of them - the one she was involved with AND the other - accordingly).
That you for this explanation! It very much describes how I feel-and I've been struggling for some time to describe it! Very helpful!