There is a familiar phrase that can crop up in meetings or discussions where people are frustrated with what is happening and not sure who to assign the work to.
“Well, what do you do? Can’t you do it?”
The problem with this statement is it puts the onus on your team members to justify their position when this is in fact not their job to do.
You hired them, you brought them onto the team, you are paying them.
If you don’t know what they are doing, it’s not their problem to solve, but yours.
Ask the question of yourself what they do before you ask them (if answered right, you won’t need to ask them at all).