I was in a situation like this once, with a mother-father-preteen son trio. As a solo diver, I ended up paired with one person from this trio, and it happened to be the mother. There was no way for me to get a good buddy out of the trio because A.) the mother didn't want a single female diving with her husband, B.) neither parent wanted a stranger diving with their son, and C.) the mother wanted to keep an eye on her son, even with his father watching over him. I'd be looking for my buddy (the mother) and see her swimming away to check if her son was doing okay. He was fine of course, but she kept mother-henning him. It was incredibly annoying, and I should have said something to her about it, but I didn't. (Also annoying: none of the trio had either a dive computer or dive tables, so they relied on my computer, which was dangerous for all of them.)
I've been diving enough to know not every dive is going to be a good one, due to any number of reasons such as bad dive conditions, or a bad dive site, or a lame buddy that was assigned to you. In those circumstances, I find myself working on other aspects of diving to improve my skills, like my buoyancy, my navigation, or in the case above, watching out for my buddy and making sure a casual (and in my opinion, careless) diver didn't end up harmed.