If they are not related, how would you know which record to display on each
tab?

You can do this, by putting two separate subforms on your unbound form.  In
the subform data source for one form, put the first table.  In the data
source of the second, put the second table.  I've not tried this, but it
should work.  Of course you'll have to have a method to select which record
to display in each tab.

This sounds odd.  You might want to post a few more details.  If your table
design is not normalized, you could be in for tons of headaches down the
road.

That's a pretty vague request so I'm not at all sure what
you need.  How about using a separate subform for each
table?