Help needed with uux and uucp through two machines

[Dave Martindale]

Uux and uucp are designed to execute commands and copy files, respectively,
only with machines which talk directly to the current machine via uucp.
Mail works because "mail a!b!c!d" generates a "uux a!rmail b!c!d" which
trusts that there is an "rmail" program on the remote machine to
send it another step along its path.  In fact, there is an "rmail" on
all versions of UNIX that have uucp (that I know of, anyway).
The same arrangements do not exist for file transfer.
Berkeley 4BSD systems have something called "uusend" which sends files
through multiple machines via, you guessed it, "ruusend" on each
intermediate machine.  But all of these machines must have ruusend, and
their uuxqt must allow it to be executed remotely.