Filemaker Advanced allows importing Tables.
You can create the Tables manually (just the fields and definitions).
Make a new Layout based on the Table you created, select all, copy everything from the separate database.
Paste into the new blank Layout based on the table with the exact same fieild names.
Scripts will have to be reproduced.
Link #1 would be a useful read
This PDF may be helpful http://www.filemaker.com/downloads/documentation/fm8_converting_databases.pdf
If you use Import Records with the "new table" option, you can use FileMaker Pro to import a table and the data stored in it into a different table.
Copy and pasting layout elements from one file to another (even from FileMaker 12 to Filemaker 11, BTW) can be done but the details can get messy for layouts that have a lot of different design details, scripts, value lists etc.