Here's One - NFS - Mounting Over Share = Nada

Here's an interesting problem ....
I re-mount USB drives onto NFS share points.
The problem is that NFS doesn't SEE that - it
only sees the previously empty dir instead.
Add a tag file to that dir and that's ALL you
will see in the share on another PC.
Tried variations of exportfs ... including the
'-r' and '-au' then '-a' AFTER doing the mount.
Sorry, the clients can't see the mount. The NFS
stuff seems to cut in very early - before the
USB re-mounts (done @reboot). If you look on the
host machine you DO see the USB drives, but
NEVER over the NFS share.
Why re-mount the USBs ? Because you can't
always rely on Linux to mount them in the
same order, used to be even the same place.
'/media/<user>/whatever' seems hard-wired
these days, but with multiple USB drives
you still can't count on drive 1 being
the drive 1 in /media/<user>. Kinda
depends on which comes online first.
Naming the drives helps, but even then.
And no, symlinks to some other mount point
don't work ... NFS just shares a link to
nowhere on the clients. 'hard' links ???
Have ONE share that's not a re-mounted
anything - THAT always shows perfectly
on the clients. Weird thing, somehow, at
one point I DID get it to work - but not
sure HOW. Just commented-out the old NFS
and fstab stuff, so I've been able to
re-try, but now none work. Set everything
to 775 or 777 for development work, but
that doesn't help.
SAMBA - this sort of thing works fine, but
I've had horrible probs with SAMBA with the
latest distros, ALWAYS intractable permissions
issues no matter the tweaks, hence using NFS.
So ... any insights on how to get NFS to
"see" whatever IS mounted to the share point
AT THE MOMENT ???
Oh, latest MX Linux.