Placing a "Colum-head", how?


I open a new topic, because i have some question regrading placing Columheads:
the aim is to put to the heat of the colum it looks afterplacing like this:

2020-08-17_14h38_11 2020-08-17_14h39_53

1.) placing of the family to the endpoint
the colums are fixed to the floors, so where is the endpoint

2.) I know the instance is just placed on point, but how can i “align” it to some reference or just place it
StructuralColums.dyn (6.1 KB) head.rfa (344 KB)

Does anybody has similar issues in project, maybe a workaround, the challlange are the slated colums