Update Summary: it wasn't as bad as I thought it was going to be, but still they had to sing KM songs.
Details: Thery were supposed to come over directly after the meeting (around 1 pm) but 'apparently' some of them felt the need to get in an hour of service first. They started wandering in at around 2:30, a car load at a time. Of course my wife had told me 3, so I hadn't put the dogs away first. Some had obviously gone home instead of service and changed into street clothes.
I invited one young elder to try his hand at archery and off we went. Soon almost everyone was in my backyard launching arrows toward my target (backed by a wall of hay bales). Good I had done my shooting earlier, because after a few demo's I never got another chance. Then we got called in for dinner. It was a beautiful afternoon for this time of the year in Poland. 50F, no wind, sunny.
Dinner went fine (around 15 total, 2 elders, 1 pioneer). Lots of busy chit-chat. Then when we were done with desert, it was time for some singing! Out came all the iPads, and out I went to the yard. They must have done 10-20 songs, some more than once. I popped in and out (Barking dogs are a great excuse to go check on things), took a brief rest in the bedroom. And finally, they left.
Everyone was polite and gracious. Nobody tried to pidgeon-hole me for a one-on-one. My wife was happy that I helped out so much getting ready for the event. So, I survived. I think the key was she has already made it clear that I have some type of phobia being around large (more than 3 or 4) groups of people. So far it is working.