What type of SQL Server Replication Allows Modifications I have an application that uses a database for each instance of the application, one instance per client. Each client wants a database for reporting as we do not allow reporting from the production system, we use a simple script to backup and restore the database nightly for each client.

Now each client wants to modify their reporting copy of the database. They want to add tables and views to help with reporting. What type of replication would allow me to keep the data in sync from the publisher to the subscriber while also allowing the subscriber to be modified with new tables, views and sprocs? Also which type of replication would best fit this scenario of a reporting database?
I would suggest Transactional Replication.  This will be more of a "Real-Time" copy of the data than the one refresh per day that you have now.  You can add new tables into the database without affecting the replicated tables.