ᐅ Bypassing Building Line Restrictions Through Lot Enlargement Instead of Subdivision

Hello everyone,

I have the following question.
My parents are going to transfer a plot of land to my sister and me, which directly borders their property.
I have marked this plot in red in the following development plan.

The plot and house northeast of the red boundary belong to my parents.

Currently, there are two garages and an old workshop on the plot. Once these are demolished, my sister and I want to build a semi-detached house there.
As I understand it now, there are building setback lines of 3 meters (10 feet) on both sides of the plot that must be observed (also in front and at the back, but these are not relevant to the question and therefore not marked). If a semi-detached house is built in the middle, a garage may be placed on one of the two setback lines, but the other side must remain free.

But how would this change if my parents’ plot were enlarged?

Would one of the building setback lines then no longer apply? Is that possible?

Best regards,
Basti