We do...when he went on the 1st date with her we sat down and discussed everything (it was his idea to be in an open relationship from the beginning).
We came to mutual agreements (such as no weekends, holidays, rare traveling) and consessions. It continues to be a work in progress.
We never discussed when in the dating process with a secondary it should be brought up that we are in a poly relationship. He tells me not to be concerned about their relationship and he will handle it. As he is keeping it casual.
I feel a bit bad I guess, I don't want her to get hurt and with him not being honest with our situation kind of hurts me a bit. And I thought mono relationships were hard!