Services offered on her menu should be listed on her profile page, and reading the reviews is how you confirm this...you can set up a review search based on what you're looking for which narrows down the number of providers you need to sort through...

I have been able to refer to existing reviews without getting into trouble, so far.  

"I read your reviews and it seems like GoodTime had a really good time. Sounds like fun! I am kind of vanilla and I have no interest in the other stuff mentioned by WildAndCrazyGuy."  

No guarantees that it will work and prevent you from being cut off or blocked, but it's a more discreet start.

Best advice is to read her reviews and hope to duplicate the best parts and avoid the parts you don't want.  

Good luck

When you do find a lady who appeals to you both, advise her that you're perfectly willing to go through whatever screening she requires but that once you're screened you'd like to be able to have a getting-to-know-you, boundaries type of chat with her prior to meeting.  She'll let you know if she's ok with that or not. (If she doesn't respond, that means she's NOT lol.)

A long, long time ago when I used to see couples, there was one who really stands out in my memory as being both very savvy and respectful.  They wanted to meet just for drinks to see if we'd be a fit, and offered me a certain amount of $ for some social-only time.  I agreed.
After sitting & chatting, and a cocktail or two, she pulled me into the ladies room: she then told she was about to describe exactly what they were after and if it wasn't my cup of tea, to just walk away.  If I was into it then I was to stay and we'd go back to finish our drinks.  They'd contact me later to set up a playdate.  I didn't like what they wanted, so I simply left.  No fuss, no muss.   I got paid for my time, felt no pressure to do something with which I was uncomfortable, and never heard from them again.  
 
To me, that was the perfect way to do it.   I later learned from a provider friend that they did this with her too, but she was up for their scenario so they played that same night.  They wound up playing many more times and even became friends to the point where she accompanied them on vacation.  

Hope that helps a little!

xoxoxoxoxoxooxoxoxoxoxoxoxoxooxxoxoxoxoxooxxoxo

 
NOONER: (noun) A sexual encounter during lunch hour, especially one that is illicit

That's the first thing. That will enable you to see the full reviews with all the juicy details.

The other things it will allow you to do is see the girls entire profile and the ability to pm her reviewers.

Then, after you are verified and have done your research, ask her for permission to talk candidly about your session. Wait for her ok before you proceed.  

She may want to talk to both of you at same time so there are no surprises on the big day. Almost all the girls want to talk to your SO before you all meet up anyway.

Finally, check her p411 page, if applicable, and other review sites. Doing your homework can really pay off in this game.

Not sure if you're providers or mongers, but both benefit from full VIP membership by unlocking all the info available on TER. Providers can get partial benefit if they have a review already posted, by linking their handle to their profile. Provider limited VIP is free, and gives you access to private messaging & the full content of reviews of you. Paid VIP runs $75 for 3 months & is worth it. Wish I had gotten it when I was getting started - full access eliminates SO many variables.

Talking About What You Want.

I ask when I meet her in person. If you're humble and sincere enough, usually I get her to do what I want. If she says no, but seems nice enough to repeat, I'll ask on the next few visits when I feel that she's comfortable enough with me.

Just trying to help the OP (and others?) with some Qs.  

The only ways I can think of to find a Provider who might meet with OP and his wife would involve doing a Review Search using "Really bi" under "two girl action".  Plus his other criteria (hair color, age, city, etc.) of course. It has been pointed out by others that some claim to be "Really bi" in order to raise their maximum score and are not at all into it or any good at it. You'll find lots of "Really bi" Providers but you'll probably have to read more than 50 reviews to find one that mentions Provider-husband-wife. How to narrow the search?

Then, I would think to search those who have experience doing FFM, even if it's two F Providers plus one M. That you would do by searching the name field for "AND".  You'll get a few wrong hits (amANDa, cANDace, etc.) but you'll get all the Name1 AND Name2 reviews. Those reviews could be a guide, but no guarantee that you'll see the same rapport with someone they haven't met before.

I can't think of a good way to narrow things down to Provider's who do threesomes with M and the non-professional F of his choice.  

Once OP has narrowed down the possibilities, I guess he should go to his Local Board and tactfully ask for recommendations. (Or is that something for the "in Search Of" Board?)  

Anyway, it's good to do your research and ask Qs.  

Good luck

I'm not seeing an Edit button, thus the reply.
Already signed up here for VIP prior to posting.