how do we manage multiple users in a CAL account

Hello Gurus,

A colleague of mine has created an instance of HANA in CAL and I'd like to access it because we need to develop together, but we're not sure how to do so. We can see tabs "Accounts" and "Users" in CAL but how do we add someone else's user to your own CAL account?

Ideally, we'd like to both manage the same account (to start/stop the instances) with our own separate users. Should be very easy to do and yet there's no indication on how to do it.

Any help would be greatly appreciated.