You can invite any YouTube channel to join your Enterprise account.
It is important to note the following:
An invited channel will only be able to manage the channel(s) they authenticate WITHOUT having access to the channel(s) authenticated by the main enterprise account.
An invited channel will receive access to all Enterprise features.
An invited channel will be added to the main enterprise account.
Admins are able to manage the invited channel from the dashboard of the main enterprise account.
The main enterprise account must have a channel authenticated to it before this option is available.