It is true they made everything up on the fly just like Lucas. Except Disney Lucasfilm wasn’t able to get away with it, and Lucas was.

Star Wars under Lucas one retcon after retcon.

The Saga wasn’t always the Saga of Darth Vader, it wasn’t always about father’s and sons and grandfathers, or a family soap opera. Leia wasn’t the sister and Vader wasn’t Luke’s old man. Obi Wan wasn’t a liar and so on. It wasn’t about a chosen one prophecy, a virgin birth and other such nonsense about blah, blah balance of the force.

So Rey being related to someone, then a no one, then related to someone is not that big a stretch.

I laughed when Emperor Smeagol was cut in half and did not foresee it. He was a bargain basement replacement for Palpatine anyway. I always assumed he was just a puppet and Palpatine was really the person behind the curtain pulling the strings. I never assumed he was literally Palpatine’s creature created in a cloning tube on Exegol.