The floor has settled, can it be fixed with a beam in the basement ceiling?

[SwiftD]

Hello!

On the ground floor (ground + basement are all the levels that exist), there are lots of bedrooms, all sloping to a certain point, which is the center of the "gillestugan" below, which itself is 40 square meters in size.

I was thinking that you could place two posts against the walls in the "gillestugan" and lay a large glulam beam on top of them. But first, you need to lift the ceiling in the "gillestugan" and there are two options according to me.
Option 1, you use "lifting posts" to lift the individual ceiling joists to insert the beam.
Option 2, you lift up the beam using a larger jack and then set the posts at the ends and lock it in place.

What do you think is best?
Is there a risk that it won't be possible to straighten the floor, i.e., the floor joists won't give in?
Is there a risk of damaging the ceiling above the ground floor, considering that the walls in the bedrooms will also be pushed up?
Anything to keep in mind?

 

[cecar33]

When it comes to lifting, option 2 is the one to go with.
But whether it's possible to straighten out the downward bend is doubtful, as it probably developed over several years and it might not be feasible to bend it back, but it might be possible to stop the process so it doesn't get worse.