ᐅ Removing roof beams – structural concern?

Hello,

I have purchased an older house, built in 1970 and slightly renovated in 2011. On the ground floor, 120 sqm (1,292 sq ft) was divided:

The upper floor is basically a shell, separated only by a narrow wooden wall:

I have access via the terrace, while the neighbor installed a foldable and extendable staircase at the red circle. As you can imagine, the roof is shared. In the last picture, eight supports holding the roof can be seen. Here you see them from the side:

In fact, there are two more supports not marked on the plan:

In the last image, two roof support beams are drawn resting on the side supports. In the previous picture, you can see the arches carrying everything; since there is no ridge beam, these beams are crucial. The problem is that after screeding, these beams would be about 120 cm (47 inches) above the floor, making the space unusable. Also, the plan includes a connecting staircase:

Therefore, this beam needs to be removed.

Now I turn to you, forum members, maybe even engineers. What options do you see? What solutions would you suggest? I am aware that the roof beam cannot simply be removed without reinforcing something else, otherwise the roof would collapse. The beam not only carries the downward load but also resists lateral forces (I don’t know the exact technical terms, please excuse me).

I have a few ideas and opinions but would like to hear yours first, without influencing you.
I’m curious to read your thoughts…

Thanks from Bolzano.