That would be an interesting conversation to have on the drive home.  

what if i run into my brother in law at Beat's lunch social today?  or my sister in law?

On the brother in law, it depends on whether he's your sister's husband or your wife's brother. If the former, I recommend blackmail. If the latter, feign confusion and ask him if he knows where the Rotary Club is meeting.

If it's your sister in law, ask her rate and for a link to her reviews.

Problem solved.

different hobby, like needlepoint.

There are a number of risks, and more to an actual session than a lunch gathering, IMHO.