oh sorry my bad i didn’t get what you need, well you can try an add an invis barrier that when your trying to place something it turns red and won’t let you.
You could have it so when you try to place a build down, check if if’s nothing touching any parts via using the return of GetTouchingParts(), which returns all the parts that are touching a certain part, and check if nothing is touching via checking if the length of the table returned is 0, meaning empty, if it is empty, place it down