RFE: pre-load hist-file from a R/O file

[Linda Walsh]

Maybe like some people, I'm playing around w/saving and storing
my .histfiles .. not on a line-by-line basis,
but with the histfiles sorted, & merged & erase dups in effect
and intention of throwing out short commands (one to 2-3 words)

I have most of that working , though right now the merging script
has to be done manually -- the file it produces is about 2.6M
and what I'd like to do is load that at the beginning of a
session -- BUT,
I don't want to just make "n" copies (for each pty/tty normally used)
and ideally, I'd like the just the new stuff to be stored
in the local history file upon exit (if an old dup was erased,
which would then "sorta" corrupt the "old-part" of the db, that's
fine, the merge script will delete older duplicates anyway)

Is there a way to specify a file to pre-load history with (other
than the current hist file), and to have it only append new entries
to the differently named per-tty file?

The way I see it working...
history is initalized with "master".  New hist gets appended
to $HISTFILE (.hist${HOSTNAME}_$TTY => .histIshtar_pts/[0..99])
and have new history appended to the HISTFILE

The only thing I'd like is  the ability to "pre-load" my history
from a 3rd file that could be read-only.

Is this doable some how? or would it require a new ENV var,
like HISTDB or HISTHIST??

I could dup-it 20 or so times, and it wouldn't hurt that much (~52M),
but that seems a bit "crude"?...;-)

Ideas?  Possible?

Tnx,
-linda