Viability of Screw UDF based on an Axis and a Face?

I am developing a UDF for screw threads and ports and need some support understanding whether a certain implementation is possible and how to manage references to make it happen. 

Insofar, I have defined UDFs with a coordinate system that every other feature ultimately points to and placed these UDFs using that coordinate system and one placed in the model, or the on-surface coordinate system option. My understanding is that the basest feature(s) appearing in any UDF will be what all the other features ultimately reference. 

Ultimately, we would like these UDFs to be placed with reference to an axis the screw goes along and the face the screw extends from. However, I'm struggling to figure out if it's possible to manage references in such a way that those are the reference prompts. I have been experimenting for a while and can't arrange datums in a way that accomplishes this. 

More broadly, I've been having some trouble defining UDFs to point to anything BUT a coordinate system, so any general advice or perhaps learning material/coursework you could point me to would be great, the docs are a little hard to understand around this point. When I've previously made UDFs based on planes that were based ultimately on a coordinate system, the coordinate system was still pulled in as a feature.  Thank you!

EDIT: I have gotten something together that references a surface, a profile datum plane, and an axis, but I'm still wondering if there's some way the profile datum plane can be defined implicitly so we only select two things.