is there anyway to group/join curves so that it acts like 1 curve instead of say....3 or 4?

i just found something that would work. Ive been creating the main parts of the building then cutting out the inside so that it has walls, then i tried to cut the windows and doors. But just now i...

it didnt work

im making a simple model of a house but when i try to cut the windows and doors one of three things happen. First is both the cutting object and main object disappear. second is it acts like it cut...