adopting IDs after the fact
This is very much a newbie question.
Background: Some years ago I, as a total neophyte, started a flat-file database for a tiny non-profit. Fields included names, contact info, volunteer activity, and monetary donations. Last year new blood correctly pointed out the need to place growing donation info into a second table, called Donations. New Blood did that, using name fields to relate Contact records to Donation records. That was, of course, a bad choice. Now we have a fragile relationship between ~1500 Contact records and ~1700 Donation records.
I want to change to a relationship based on ID fields. First I would create an auto-enter Contact ID field. Then I would populate existing Contact records with a set of serial numbers, using Replace Field Contents. Next I would create a Donations ID field.
This is the point at which I lose focus: How to populate the new Donations ID field? Once that is done I would redefine the relationship (surely needing advice to do it right) to one based on IDs, not names.
So, hoping this is the right question, how should I populate the Donations ID field? I guess brute force would work: Wade through every Donation record one by one, typing in the appropriate contact ID. Is there an easier way? Do I have a large conceptual blind spot? We're using FM7.