QB just posted on General about a way to indicate the Provider is willing to host "couples." To be more precise, a couple in this case is a group of two, usually M+F, who want to visit a Provider together. That is DIFFERENT from "doubles" wherein two professional Providers host a single client, usually M, as F-M-F'.  Usually, adding another simple data field shouldn't be too hard or break things. "Field Name - Check Boxes" "Will host Couples [ ] Y [ ] N".  (It might need more detail: FF couples, MF couples, MM couples.)  
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So that's QB's suggestion but that made me think of another suggestion. This one is harder to implement because it would be totally new code. And your input would help.  
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Suggestion: ADD A free text COMMENT BOX FOR THE PROVIDER TO USE. Short comments only. 100 or 200 characters, max? Should it be a something to be edited by the Provider directly or to be submitted to Admin to check for content before posting.  
Allowed: "I also enjoy hosting MF couples but there isn't a data field for that yet."  
Disallowed: "Reviewer xxx is filthy, dirty liar. I never met him. I don't do [this] or [that]. He should rot in hell after being expunged from TER."  
You get the idea. Good? Bad? Need more input? How many characters is enough?