Extending use of my USB drive

[allen meyers]

Presently I confine the use of my external to a huge data partition
which I unmount and unplug after use.
What I want to do is use it as well for a 2nd Linux OS and I merely want
to be sure I am leaving nothing undone.
My thought was to insert gparted live CD and resize external and
install. Is there something I am missing.
Please advise
I can only hope the tone of my request evokes no further comments on
that thread.
Seriously I appreciate the list even in its present state of flux.

Allen