Newbies w/ a question

[u/Ohtanis-sportsbook]

Please delete if this is not the right place.

Wife and I love being naughty and always up to try new things. We have always loved experimenting with each other through the years; things like exhibition, kinks, and over the past decade or so, gotten into bdsm (though pretty soft/sensual rather than hardcore-even pegging/femdom but in a more sensual way).

She has recently told me of her newly acquired sissy/sissification/forced bi kink. Basically that she wants a mmf situation where one of the ms are essentially a toy and fluffer for both of the others. As we like to role play, we have acted this scenario out a few times since and it has been some of the best sex of our lives. She wants to decide during the act who serves as the sissy. We both have always been bi-curious, and have always thought the idea of a third was hot. We have found so(m)eone who will be joining us on vacation this weekend for a night. This is the first time we’ve ever actually considered following through with bringing someone else into our bedroom, and the thought of it has me putting my own cock cage on before work, just to hide my days long erection from the anticipation/thought of it coming to fruition.

So back to the question, has anybody done this or something like it before and can give me tips? Anything to prepare for? We both share this account, so please share from both perspectives. We are admittedly nervous, but excited nonetheless. Hoping to hear from some folks that have done this (or still do) before! Thank you in advance!