My stewards, more than one, have told me that many grievances have been filed and lost on the situation I described.
One working, one observing...I said the same thing. One steward even said, "I agree with you, but I've lost that one too many times."
Honestly, I'm one more stupid loophole away from calling my BA and asking for a comprehensive breakdown of all of the rules and exceptions for filing on sups working. It's like anything goes these days.
I guess it's possible that the stewards are lying (a very troubling turn of events if true), but they are adamant that the new hire can be 100ft away...just as long as they're "in the same area."