MFM involving an ex

My partner and I have been talking about having our first MFM. I’m all in as it was originally my idea because I want to see her get as much pleasure as I can possibly deliver.

She’s been talking to an ex that she’s been friends with for years and it turns out he’ll be moving back closer to where we live after an overseas assignment. She has asked him to be our third. I’m good to go as long as we meet first and make sure the vibe is good.

For those of you who have experience involving an ex, what have been the pros and cons? Have you experienced any pitfalls?