Can we all try to remember that this child is nearly 10? Some suggestions are great for 4 year olds but really, by nearing 10, they are a bit much IMO.
That's just bizarre. Did you stay and figure out that funky communication there? Stop by City Hall to leave an anti-kudos for that CM?
Always a great idea especially if the kid hasn't been to Disney before. "Uniformed Cast Member with a nametag behind a register" is a tried and true method.
It's a good idea. We don't do that anymore since my son was around 9, but especially since the aunt isn't buying the clothes and might not be as familiar with what he has on, good idea.
It might be a terrific idea to talk with your sister in law about what SHE does when she is out and about with him.
Meaning he'll have to hold it until you find another bathroom, right?
With a non-single bathroom he can always go in, see if it's empty. If empty, head on in while you wait outside (this isn't the time for being efficient). That way you see the people who might go in after.