Hi,
some building like the landing stands have roads predefined in their blueprint. That means it’s not possible to place them on a existing service road - the road must be demolished first. On the other side, for example bus stops, taxi stops, etc. can be placed on existing roads.
I assume for stands, it’s necessary to have the service roads within blueprints because non-remote stands must be adjacent to the terminal. If it’s not possible to remove the roads from the blueprints because of this, I suggest that it should be possible to place the building if the underlying tiles are either empty or (service) roads.
Might be that other buildings than stands will benefit from this as well.
Regards