attaching a terminal to 'join' another?

[Jim Stapleton]

Sorry if my question is a bit confusing - I'm not even sure the proper
terminology, so I don't know what the best way to start looking is.

I'm rebuilding a system at home, and I'd like to check how the build
is going at a slow time at work sometimes. I can connect to the system
from work (ssh into my main box, and then from there, ssh to the
system I'm working on). I have a terminal opened on that system
(actually, another ssh session fron the main box), and I'd like to
have my new connection attach to that terminal session, if possible,
so that I can just pick up where I left off, and monitor it from here.
Is this possible?

Sessions
main desktop terminal A [ssh]--> workstation terminal A (where builds
are currently being processed)

work desktop terminal [ssh]--> main destop terminal B [ssh]-->
workstation terminal B


I would like to have workstation terminal B intercept workstation
terminal A, or main desktop terminal B intercept main desktop terminal
A. Can it be done? Where do I start looking, what are the words and
phrases of interest? I tried looking at both the bash and xterm
commands/man page, but they are rather long, and I'd miss what I was
looking for without having a clue in advance.

I'm guessing something like /dev/?tty?? might work, but how do I
figure out which tty to use?

Thank you,
-Jim Stapleton