poudriere merging multiple ports trees

[Russell L. Carter]

Greetings,
I am completely ignorant here and am looking for up to
date advice on how to get poudriere to build and make
available package sets from multiple ports trees.  I
see there is a port "portshaker" that seems to do much
of what I want.

I can think of possible alternatives:

I can reasonably expect to have my local ports not
conflict with already existing ports (could be a common
prefix in the name).  Since I'm using git, I should be
able to maintain my own branch which layers my own ports
over upstream and git pull, merge from upstream.

or

I can duplicate the structure and metadata of the existing
ports tree and add my own ports and leaves in the tree.
Still have to maintain unique names.  This seems to be
what portshaker does?  I am guessing that gets me a
single package repo.

or

Have two ports trees and generate two package repos, but
then dependencies would be redundantly built, I guess.

What do the professionals do here?

Many thanks,
Russell