Curtain wall border Mullion - Profile to align at the centerline

[libre]

I am trying to design the border mullion of the curtain wall, in a way that its centerline alignes to the border gridline.

For default the border mullion aligns the external face of it to the gridline,
but I would like it to act as the internal mulluon - aligning with the centerline.

How can I make it?

Thanks a lot!

[libre]

I would like that the border mullion does not stop at the end point of the curtain wall system but that the border mullion has its centerline at the curtain wall end point.



thanks