How to update People Group?

Hello,

We are in need to add additional values to the People Group. Our implementation team over 2 years ago configured the People Group for the Retirement Eligibility plans that the college offers. Now there is a need to add additional retirement plans to the People Group, but we are unsure how this can be done as our implementation team left no documentation on how this was configured. Any advice or information how this can be done?

Thank you,