User variable on shared member has hierarchy from original members. Is there a workaround?

Summary:

User variable on shared member (all shared members created without hierarchy) has hierarchy of original members anyway. Is it possible to work around this? 

Content (required):

I would like to build a complex form. For this I need the months January - December without hierarchy structure to be able to work with the functions of the form manager. The months must be selected by a user variable. In our period dimension the months are in a hierarchy (YearTotal-Quarter-Months). So I have created a flat list of shared members Jan-Dec in the period dimension. After that I created a user variable with this shared members. This user variable I want to use in the form.