hmmmm...
Any set I ever had was like you mentioned... four screws through the bottom and into the seat.

Hopefully someone can help - new upholstery made all the difference in my dining room!

If you're having an upholsterer do the work, just give him the whole chair, he'll be able to deal with it. If this is a DIY project, upload some pictures.

We intend to do the work ourselves. However, my wife has talked with an upholsterer to ask whether dining chair seats are usually glued, as well as screwed on. He says that they are not usually glued, and has offered to look at the chair to see whether the seat can be removed by tapping it with a mallet, now that the screws have been removed. We've only tried one chair at this point. It may be that the other seats will come out just fine.

I don't know if it depends on the furniture brand but my FIL re-upholstered his old dining room chairs and they were not glued. He used thick fabric and a staple gun. They turned out ptetty nice.

Yes... but to use that "thick fabric and a staple gun", you have to remove the seat! That is what is holding the OP up... the seat won't come out.

Fabric seats are never glued in place. OK, never say never. But, I've never seen it. I have seen where backs have alignment pins, perhaps your seats have those.

the screws are typically on the inside edge of the leg of the chair where it meets the seat, did you look there? I have never seen chairs that aren't constructed like that, and once you remove the seat - 15 minutes with a staple gun and you have new covers..couldn't be easier

Post a picture....so people can better assess the problem.
Linda C

How do these seats come off please?

I have the same issue. The seat and the back have no screws.