I think that's more like in a regular game, where you can select players or NPCs as targets for healing spells and such. It doesn't seem to me like the players have everybody's health bars visible all the time, either. I imagine that would get quite distracting. The field monitors or operators, or whatever they are talking about, seem to open a bunch of windows to monitor the group's status. But it could be that they just select the players (or NPCs) nearby for that.
But then again, I suppose it could be possible to add whoever you want in a group. It would be a jolly function in an MMO, even if it had no other purpose but to be able to quickly open those windows or send a message to everybody. However, I'm not so sure that's enough for telepathy. In a more prominent scenes they have stated you can only make a phone call to people who you have on your friend list. Rudy clearly didn't qualify for that. I'm afraid I don't remember scenes where they would have talked to Rudy telepathically, either, but that could be because I generally find the kids so boring I only watch their struggles with half a brain. When I rewatched the show, I kept skipping their scenes...