One of the things I’ve observed is that leaders sometimes make decisions for other people by deciding in advance that the other person is already too busy for a particular new challenge. Therefore the leader doesn’t ask them. That’s presumptuous. By making that statement, we are taking the place of the Holy Spirit in assuming that we know what God’s will is for the other person’s life and that it’s already filled. We’ve decided this new opportunity is not for them.
Better to make a list of all the people who are possibilities, whether or not you think they are available or would be interested. If God impresses it on you, go talk to them. You don’t know what God has been talking with that person about and what they’ve been sensing in their life. It could be that this opportunity is precisely what they need to do, even if it means releasing some of their current tasks to someone else. God may be actively at work refocusing them on new challenges.
So rather than prematurely ruling people out for taking on a particular challenge, allow it to be an opportunity to for that person to process what God may be saying to them in this season of their life. That might mean saying no to this opportunity, or to things they are currently doing. But that’s up to them and the Holy Spirit to determine, not us.