I would definitely say that they have already agreed that they are open to it, and they are just tossing out signals to you and waiting for you to jump on board
We have 1 rule. No playing without the other present. You get ...... n horny. Msg the other that you're bringing someone home, or that someone is coming over for some fun.. its worked for us for years
My wife has recruited well endowed guys from her GFs. So they know I'm very small when soft and avg hard. But that I enjoy sharing my wife with a big cock