Rotation parameter

[shelmsGYSXD]

Is there a way for me to add a rotation/swing to this family?  If you see my attached photo I need it to rotate/swing from the red dot. And I need only whats highlighted in yellow to rotate/swing. The top part should stay fixed in place. Its already a nested family with other parameters so I'm just confusing myself now trying to add onto it. I attached the file as well.

[SteveKStafford]

I've attached a mock up "brace bones" (Revit 2025) to show how you could constrain it using a Reference Line to host the brace form(s). If you really want to specify an angle then you'll need to use some trig to calculate the length and depth required to reach the base of the brace.