Thankyou for presenting such a rare and valuable collection of music however I think it may be useful to inform future readers what quartet sets are incomplete.ie. Forster - vln 1 & 2, vlc missing /
Pleyel - vln 1 & 2, vlc missing / Griffin vln 1 & 2, vlc missing.
Anyway

It would be nice to think that due to the access provided by your resource the missing string parts may eventually be located and added to your collection.
Bravo