How can one day a man be my 23rd GGG and on another my 26th GGG?

George,
don't forget that he very easily could be BOTH your 23rd and 26th GGG, through different lines. That far back a three generation difference is still within reason.

Also, the tree itself is undergoing a lot of changes and merging. So if, for example, you had an incorrect connection to him, through a line that was missing a couple of generations, and this was merged-fixed into a more correct line, then you would see such a change.

Wow, Shmuel, I really needed that explanation. Thanks so much!

Here's a recent example George. My 3rd great grandfather is also the brother of my great great grandmother. His granddaughter married his sister's son. So I'm related to him two ways. Once you go further back, there are likely multiple paths between you and any ancestor, especially given how much marriage there were between relatives.