Not that I'm aware of.  But it sounds like you know your
Access, and that's a great start and can solve your mail
merge problems.  Everytime you create a Database in mail
merge it saves it as an Access file (table) and it also
saves a Query too.  In other words, whenever your in mail
merge its data is being screened by the Query, so if you
edit that Query, and add more tables to it and
create "Joins" between them, then BINGO, you've kept your
tables sepate, but bringing them together under one
Query, and you're maintenance will pratically be a breeze!

If you don't know much about "Joins" or "Relationships"
then you could create a third table that contains both
data and then edit your query to only contain that 3rd
table's data, but then any changes you make in tables 1
and 2 will have to be updated (copied and pasted, or
appended) to table 3.

Or lastly, you could export all of your tables into one
Excel work book and use that instead. I hope this helps.
www.dreamforce.us

Use a Select query in Access that links the two tables and use that query as
the data source.

Be aware though that Word cannot really handle a "multliple items per
condition" situation.  Access alone can do it far better using
reports/subreports.