Curtain Wall Mullion Orientation

[stevomatic]

I am working on a faceted tower in which large expanses of panels will be following specific planes. I would like the outside face of the mullion to be parallel with the plane and the other three sides of the mullion to be parallel with the floor. It seems as though I can do one or the other but not both by manipulating the orient to host or orient to global z parameters. I have attached the family with nested mullion family. I expect the facet angles to change throughout the process so would prefer if this was automatic, based on host, rather than providing an angle input parameter to manually set it.
Best,
Steve