That's.. not quite right. Did you get this from skimming Wikipedia? It's true that the first TNG ep featuring Alexander had someone other than Bonsall play the role, that kid stopped acting almost immediately after. Bonsall played Alexander for the rest of TNG. They age up Alexander significantly for his return in DS9, so, yeah, needs a different actor. There's a TNG ep where Alexander comes back from the future to try and correct what a shitty character they made, so that's probably your "fourth" Alexander and I'm not sure where the fifth comes from.

Edit: Looked that one up. The "Fifth Alexander" is a technicality. Worf has a picture of him and Alexander as one of his personal effects that he brings with him onto DS9 and the person in that picture "playing" Alexander is uncredited, but makes no other appearance other than being in that photo.

Hey I'm actually baffled by your reply. You clearly didn't know there were 5 actors who played Alexander, because if you did, you'd know they were mostly one offs, from a different series at a different age or, uh, a photograph. It's like you saw my comment, decided to reply to it, searched "Star Trek Alexander actor" and read the headline of the first result, a Screen Rant article titled "Star Trek: All 5 Actors Who Played Worf's Son, Alexander", and decided "That's enough info, I'm ready to reply to that comment."

Clearly you didn't read the article, otherwise you wouldn't reply the way you did, because you'd know why there's 5 Alexander's and it wasn't because the writers were trying to fix the issue.

I'm not mad or annoyed or anything, I'm just utterly baffled by how you use the internet.