Start outer screen session with
screen -c .screenrc.outer
And the inner session with
screen -m -c .screenrc
Then you're set up to use Ctrl-\
as the escape sequence in the inner session,
and Ctrl-^
for the outer session. Detaching with Ctrl-^ d
preserves the
layout of the inner session.
Happy screen'ing.
scottgwald 22.07.2014