Regroup allows for an unlimited amount of Network Administrators. You must be a Network Administrator in order to assign those privileges to another user.
From the top of the screen choose "Groups" and then "Members" you will be taken to the "All Members" area. Once there you have the ability to search for a user by first name, last name or phone number.
One the users name has been found you simply hover over their name and you will then see a three-dot menu to the right of that row check the box "Network Admin"
Once checked that user will have complete and total control of the network just as any other network administrator.
Once the permissions have been assigned you can hover over the same three-dot menu and you now have the ability to control the "Notification Settings" for that admin as well.