If you want to filter friend requests or iCloud messages, here's an example.
When you set up the device, make sure it's using a sub-address of your main email. This is even more convenient if you set it up on the same address used for your own Apple ID. Now all the iTunes receipts and subscription notices and everything will come to your email address. With some rules or filtering for that address, you now get all the information from that account just like you do for your own.