The intention of the OP is not entirely clear to me yet: is it about modifying the only two-family house floor plan available on the internet that fits the external dimensions without involving an architect? - A 60 cm boundary distance leads me to fear that the mayor must be the cousin of the one who is causing mayoral mischief in the community of , because this is nonsense straight out of a textbook. Extension obligation yes or no, but extension obligation a little bit, that doesn't work. I have already understood that there is no development plan here, but then the §34 framework must either be supplemented by a local statute or the requirement of the 60 cm boundary distance is the mayor's private wish and does not apply. In fact, from the surroundings, I hardly see a reason to deny the wish for a unilateral boundary extension here, but it is not clearly determined whether this should be wished for the west or east boundary. Building free-standing within the actual building window with a normal side setback is also, as I see it, not deniable here. Roof windows seem to me to be possible here, limited by fire protection.