How do I set a team as proxy for a users transaction approvals?

Summary:

For one transaction, Change Salary, I want a team to act as proxy for the top person in our hierarchy. When transactions are submitted and go for approval, should the approval chain reach the top person in our hierarchy, I want an admin team to pick these up on their behalf.

Content (required):

We use standard supervisor hierarchy to identify line managers and go up the chain for approval either one or two steps depending on some variables. Should the approvals reach the person at the top of our hierarchy I want an admin team to process them on their behalf. I know you can set an individual as proxy but can you set a team as proxy? Maybe through a security role/AoR etc.