This guide also works if this person is online but maybe in a different space or you can’t click on their name for some reason to add them. And this works for blocking, adding and removing people anywhere on the network.
The one thing that this search feature isn’t is a search function for your current friends list.
You can find out who is in the room with you by selecting ‘Here’. It’s a nice way to find people to block who are being disruptive and may be hiding from view, but you can identify them and block them this way.