I haven't used it, but there's a tool called FMMIgrator you might investigate.
And I think there's a template offerred for sale that already combines a number of the starter solutions and is offered under the name "starting point".
If you have fileMaker advanced, you can copy and paste tables from one file to another--basically the same as import records, but without importing any data.
You also do not actually need to import or paste the table. You can also go to Manage | Database | Relationship add a new table occurrence object and use the add FileMaker Data source option to connect the table to a table in another FileMaker file. But that still leaves you with the need to link the table occurrence to the others in the file just as you would with an imported table.
And if you are careful, you can copy and paste all the objects from one layout into a new layout in the combined file without needing to use the inspector to update all the field and table occurrence references. The trick is to have the needed table occurrences and relationships in place first and with exactly the same names as is found in the original file from which you are copying--sometimes you rename an occurrence or two and then change the name back after you have your layout working.
Here's a link that describes copy and pasting a layout in more detail, but it's not for the faint hearted: Importing Layouts
Thanks for the tips Phil, I'm definitely going to follow your advice. I have looked into FMMigrator, it seems like it is geared more towards combing FMP databases with other forms (MySQL, Oracle, Access, SQL Server, Sybase, DB2, OpenBase, PostgreSQL, FrontBase, SQLite and Valentina), but also has a table combining feature that could work. The biggest drawback is that the packages start around $200 and get as much as $2000. For that price I'd rather start myself.
Thanks again for your advice it is always welcome.
If you do merge some files on your own, the Database Design Report that you can produce from FileMaker Advanced can be very helpful--well worth the extra dollars spent if you don't already have that version.