An infinite family seems to refer to an infinite collection of solutions that are all related in some sense. An isolate or sporadic solution is a solution that is unique and unrelated to other solutions. They are both terms used to categorize solutions.
And I have, so far, 5 infinite families with, respectively, 2, 4, 8, 16 and 32 pieces.
But details matter, and you might start to question what it really means when I say "piece." Does the definition I've given really capture your intuition?
I think 8 pieces also works, but I think that may be it.