Adding a column to the metadata db

I have >200 DVD's which take up a lot of space in their original packaging.
So my plan is to Handbrake them to a videa library and serve them with Serviio.
This all works right now with my experiments of 6 or so movies.
Now what I want to do is file the original DVDs in plastic envelopes 2 per envelope. The envelopes com pre numberee.
Also take the printed covers and file them in a binder in plastic covers whose number match the DVD envelopes.
This will reduce the space from 9 shelves to a single box and binder.
It would be very cool to be able to add the envelope number to the metadata db.
How could I do that?
(P.S. I am a retired Mac developer so I can hack code if need be.)
TIA for ideas.
respect
Peter
So my plan is to Handbrake them to a videa library and serve them with Serviio.
This all works right now with my experiments of 6 or so movies.
Now what I want to do is file the original DVDs in plastic envelopes 2 per envelope. The envelopes com pre numberee.
Also take the printed covers and file them in a binder in plastic covers whose number match the DVD envelopes.
This will reduce the space from 9 shelves to a single box and binder.
It would be very cool to be able to add the envelope number to the metadata db.
How could I do that?
(P.S. I am a retired Mac developer so I can hack code if need be.)
TIA for ideas.
respect
Peter