This is a hack, plain and simple. If you really want to move the table, the best way is to create a "temp: table on the new filegroup. move the data, drop the existing table, rename the "temp" table and then re-create all of the FK's, constraints, and indexes.

It's a bit of a PITA but it's the only way to ensure the whole thing gets moved properly. Besides, that's pretty much what SQL Server is doing behind the scenes anyhow.

By best practices the nc indexes should (probably) be on their own filegroup anyhow but that's a different issue.