To clarify, I'm not just asking what pets get referenced the most often. That's simple enough to find, and it's probably one of the 2009 dogs that's been around since the beginning. (Sunback, perhaps? I'm not sure, I'm fairly new here still.) Rather, I'm asking the question of: how many times is a pet released that's inspired by an existing pet, and then a third pet is released that's inspired by the second pet (and only indirectly by the first!), and then a fourth pet is inspired by the third one, and so on.
This question came to mind when I was pondering my favorite second-generation litter, the eastern dragons from July of 2023: a second-generation litter in which one of the parents was a GUPPS. Since a PPS outcome from that litter received a GUPPS version last year during Advent, this means that we have a GUPPS of a 2nd gen of a GUPPS of an original pet, four layers deep, as you can see in this family tree:

I had far too much fun drawing the little dragon icons for this tree, and honestly half the reason I'm posting this thread is to show them off. But I'm also genuinely curious: are there any larger family trees, ones that go deep as well as just wide? Obviously, any 3rd-generation litter is going to be wider than this, with four entire litters worth of pets in the first generation. But how often do derivative pets then go on to get their own derivatives?