Does fmDataGuard support multi-file solutions?

Yes. Each solution file requires a Table Occurrence to the AuditLog table, which can reside in any one of the solution files, or ideally, in its own file, and as a Best Practice, on its own FileMaker Server. Are there any limitations or database requirements which must be met? There are a small number of limitations as well as requirements that must be met. See the documentation which comes with the demo download for details.