I think I'll just ask directly at the office.
The most sensible question in my opinion would be whether, by integrating the building into the semi-detached houses environment, one would be willing to combine the two plots and then allow three or four residential units on this entire property.
Regarding the fundamental consequences, such as the number of full floors, floor area ratio, floor space index, and so on, they will refer you to your own eagerness to learn (or to an architect). The offices do not provide active building owner consulting.