Multiple Syncadapters in One Application

I need to have two separate syncs in my application. One is done every 12 hours. Another is done every week. I want them to be under the same "account", so each type of synchronization can be turned on / off separately.

Actually, accounts are mannequins - I don’t need these functions, so all my authentication methods return null.

But I can only get one sync to display the account. Any idea how I can achieve this?