It depends entirely on the structure of the databases. This can be
quite simple - just a few Append queries - or almost nightmarishly
difficult if there are duplicates, partial duplicates, conflicting
primary keys, etc.
The short answer is to open one of the databases (the "target", which
will contain all the data eventually - MAKE A BACKUP FIRST!) and use
File... Get External Data... Link to link to the tables in the
"source" database. Run append queries, update queries, etc. as
appropriate for your particular situation - they're all different!
