Yes, it is possible to either link or combine the 2 files. Personally I would combine them. Otherwise you'd have to Delete the Contacts table from Lending Library (which is the smaller of the 2). The first thing to do would be to add the tables from Library which are not in Events Management; Assets and History. Then you'd need to recreate the table occurrences (TO) on the Relationship Graph which they required.
You already have the Contacts table, but you'd need to add its TOs to the Assets & History table occurrence groups (TOG). I had to create a single field in the Contacts table (One) in order to do this; and the naming convention is different for the Contact ID. But that's no big deal.
You would also need to add the Scripts from Library. You don't need most of those in the Contacts section, but you do need the 2 "check out" ones.
This could all be done with FileMaker Pro, via Import. But I use FileMaker Pro Advanced, which lets you copy/paste.
This is what the Relationship Graph should look like after combining them. I have colored TOs of the same base table (via the tool to select TOs of the same table).
This Google search brings up several useful links
This link was one of the better in the top ten