Restrict who can add users to the group Domain Admins

Hi Guys,

In the domain admins group, we have the following situation:

-----------------------------------------------------
<Individual user accounts>
<Group accounts>

So, for example,

----------------------------------------------------- domain admins group
Bob
Sue
Steve
Server Admins group


What I want to be able to do is to restrict who can add or delete members of the domain Admins group.

So, for example, is there a way to stop current members of the domain admins group from adding or deleting members of the domain admins group?

What is the best way to do this?

Thanks everyone.