Figure out what you want to include in the database/archive/registry... Which could include nothing but the VIN and the owners name (and major options/color/trim/etc...possibly)? Or it might be more, but as you try to include MORE, your problems increase and the owner's hesitancy to provide the data increase as well.
I have a 42 MByte file I've been developing for the past 10 yrs. Initially it only included the major items: VIN, info from the cowl plate, data from the engine, trans, etc.. and some historical information as to when I purchased it, who from, and the state of the car when I purchased it. After I found/registered on CRG, each time a new 'topic' came up, I'd check my car and make notes and/or photos of that part on my car. As a result of my desire to keep the car original, and thru my involvement with those on CRG, I've now included photos and notes on essentially everything we've discussed (from my car). I keep the photos included in the *printable* file small enough to fit in a 1/4 page but make sure the 'info' is obvious (on my computer, I keep the large highest resolution files in case I need to refer to them). When I rebuilt my brakes, I took photos of the calipers, dates, etc.. wheel cylinders, the original rear brake shoes/hardware (which I retained). When I replaced the soft parts (rubber brake lines) I retained and photographed the originals (due to Steve Shauger's suggestion to do so). I would not pass along ALL of the information I've gathered to such a registry; it would only be passed to the 'next owner' if I'm alive when that happens..
BUT.. I would pass along relevant information (dates, codes,etc) to such a registry if we arrive at a reasonable level of information that the folks here on CRG are agreed to. In fact, over the last 10 yrs, I have included info and photos of the parts from my car in CRG threads when it was useful to answer a question or help another CRG member.
I don't know if this helps you, or not, but FWIW, this is what I've done on a personal level.
