if you using the SqlCeClientSyncAdapter, then yes, i think you can dynamically add tables to the SyncGroup. you mentioned you're not using stored procs and triggers so am assuming you have the sync sql commands hardcoded, you can then dynamically replace
the statements.
have a look at the Sync Adapter builder from here and see how much of it can you reuse for your scenario:
http://blogs.msdn.com/b/sync/archive/2008/08/13/2-new-sync-samples-download-only-adapter-builder.aspx