Google (or search in FileMaker forums/blogs) FileMaker Separation Model
You most likely at this point will have to start importing one table at a time and match up the fields to migrate all the data. Or using FM Pro Advanced, copy the new tables/fieldsscripts into the existing database. You can also link the two databases.
There is no easy built-in process. It helps immensely if the source and target fields are the same name.
There are File Manipulation plugins and some can help.
Thanks for your answers - I have FM PRO advanced. Also the source and target fields are exactly the same in all respects - didn't change anything - guess I'll go looking for a plug-in.
But if the new sections of your db have no data to move, why not simply add the new elements to the old db? I assume when you refer to the new db you mean it's the structure of the old db with elements added. Since you have Advanced this should be simple as long as you're sure what you added.