Building permit for other windows with developer

Good day everyone..

We are building a KFW55 house with a developer. Actually, two separate terrace doors are planned here. As a special request, the doors can be connected and a lift-and-slide door can be installed.
We would now like to have a double door instead of the sliding door. We were told that this is not possible because the entire chain (building permit, KFW calculation, structural analysis, etc.) would have to be redone.
Is that correct? I thought it didn't matter which window is installed if the opening is already there and approved.

Can someone tell me if that is really the case, or possibly just an excuse to avoid extra effort.

I would appreciate an assessment and maybe even a professional opinion.

For the building permit it does not matter, for the structural analysis maybe it does. But if you build with a developer, it ultimately does not matter why he does not want to. Having less effort is definitely a good reason...

I can also imagine statics: it is simply easier to span one meter above the window than three meters. kfw should not be affected if the window area remains the same. The building permit itself should also not be affected; if necessary, a change request can be made.

No, the opening is already larger. He wants to switch from lift/slide to double-wing. In my opinion, that shouldn't make a difference, but I could be wrong since I don't know if the fixed part of an HS door might be statically load-bearing

He wants to switch from lift/slide to double wing.

No, he now has two singles. They could have been connected into a sliding door, but he now wants a double wing door. So both singles pushed together. Right?

In both cases, however, 2 single doors = 2 holes in the wall become ONE wider hole in the wall. And, I don't quite understand the structural argument either. An important piece of information might still be, how wide should the whole thing be?