There are five owners' marks, and I've been able to read and identify three of them: the two most recent and the one that is probably the oldest of the five. The two newest ones are stamps that are well attested and weren't that hard to sort out; the oldest is a mess — a colleague in a different field looked at it and asked me: "What makes you even think that's language?" — which, not to toot my own horn or anything, was a real triumph to both decipher it and identify it as the mark of a French book dealer with particular known interests in Andalusi work.
But I'm really stuck on the other two.
I think that the second one might begin: "zeh ha-sefer shayach le-yosef" (this book belongs to Joseph) but I'm not even sure about that. But if anyone out there is more familiar with early modern Ashkenazi hands than I am and can make some sense of these, I'd be beyond grateful, would acknowledge you in an effusive footnote, and would be more than happy to send you a batch of cookies, too, if that's your thing.
So here goes. Click to enlarge: