T&T: Interfacing Autopilots with dual stations???

[Robert Pelton]

How do dual GPS chartplotters work with the Autopilot.
I have just installed a Raymarine 6000 and I have a Northstar 951 at the
upper station and the 952 at the lower station.  The Raymarine sincs
with the 952 only, even if I move it to the upper station. Do I need to
install a manual switch or something?
Also, the upper station furono only sincs with the 952 as well.  It all
worked fine before replacing the old AutoHelm 8000.  The yard who
installed the new system now will charge me labor to look into this
problem.  I am considering taking it to a "Marine Electronics" only shop
in the area

Bob