You could do something like that two ways.
Cheap way: Make an invisible CanCollide false brick, and weld it to the other part.
Hard way: Use BodyPosition, or a script.
if you mean, ile a brick that will stay still if you go on it, but if you use say, a buzzooka to blow it up, itle fly off? first try weilding it, if that doesnt work try glueing it (use surfice tool ;D)