Saving and compiling them as a map entity is the same as when you build a regular level, the meshes don't get merged but just the information where which entities need to be created with some initialization information gets saved, not more.

The vector-solution is an easy, relatively fast and flexible solution, you should give it a try.
One hint:
vec_diff(my.skill60,my.x,my.parent.x); // once at the start of the action
...
vec_set(my.x,my.parent.x); // in a loop
vec_add(my.x,my.skill60);

The code above is a very simple way to keep a non-rotated entity at the same relative position in respect of the parent entity (your room), even when you move the latter.