Lift "sunk" upper floor

[mag00]

It's a bit of a catch-22 for me right now. It started with a leak in the upstairs bathroom, followed by a confirmed leak in the downstairs bathroom's drainage. I suspect that the cause (partly?) for the leak in the upstairs bathroom (the waterproof layer) is that the upstairs is poorly constructed and sways (large movements).

The upstairs is only half, i.e., it is an open solution with a balcony overlooking the living room/hall. Across the outer walls, they have used 195x45 beams over a span of about 7 meters, without a load-bearing wall or beam. This naturally means that the upstairs has settled significantly and sways noticeably when walking on the balcony. It has been in the back of my mind to address this in the long term, but with this bathroom issue, it suddenly feels like it's "time." It seems clearly unwise to completely renovate a bathroom upstairs and later lift the structure. It seems like a recipe for ruining the waterproofing.

So, I'm just a happy amateur, does the expert panel have any tips and tricks on how to do this? Or perhaps someone advises against attempting to lift?

My thought is that first, one or more pillars need to be built in the crawl space to reinforce the floor where I will then place the load-bearing posts/beams on the lower floor. Then lift the upstairs with a jack and props (how???) and then place a glue-laminated or steel beam across under the upstairs floor structure. This beam would then be about 5 meters, as that is the distance between the outer wall and the balcony railing. The beam would then rest on beams in the outer wall and just below the balcony railing. It is also possible to relieve the beam halfway as I have a currently non-load-bearing wall there that I can reinforce with a post.

The thing is, I cannot "recess" the beam into the ceiling, so it will need to be visible/built into a box below the lower floor ceiling. With a relief/post also in the middle of the beam, I assume one can reduce the dimension somewhat?

It's hard to explain, so I'm attaching a picture where I have attempted to draw where I imagine the beam should be. The beam is the red scribble. I have also tried to show directionally how the 195x45 beams are positioned upstairs if it wasn't clear above, and with blue marked where the post at the balcony edge should be.