Doodad on a Doodad

i wanna make a doodad upon another doodad (the one i use is invisible platform)
How i do this? i guess i have to do something in object editor, but where and what?

U cannot place invisible platforms directly on eachother (besides, what need would that have? it will walk on the upper one anyway). U can however place them over eachother but not exactly on same spot: hold shift while placing them.

im gonna place them on another doodad....

then delete the pathing of the original doodad if holding shift while placing doesnt work.