This is reflective of spreadsheet thinking. In a relational database, you would never have tables that constructed like this. Instead, you would have a single table with an additional data field. That field would serve to collect the counties into groups. if a county moves groups, it is simply a matter of changeing the value in its group column. You wouldn't need to change anything else. The other advantage of a properly normalized schema is that your queries are simpler and there are fewer of them. Instead of having a different query for each table and all the overhead caused by that, you have one query that either prompts for a group or refers to a combo box on a form where you have selected the group you want. I'm sure fixing this problem will also allow you to eliminate forms and reports as well as queries.
So, since you need to make a big change now, make it the right change and it will be the last time you have to deal with this problem.