I am sorry if that has already been discussed here, but the brief search didn't render any results.
My son's Global Entry is up for renewal later this year and I am tempted to switch it to Nexus as I did with mine before (plus it is $0 for a child which is an extra plus), but not 100% decided yet.

That said, I have 2 questions:
1) Does this transition process (Global Entry -> NEXUS) for a US citizen always require an interview? Not a biggie, we live ~4hrs from Niagara Falls, so might make a good weekend trip, but wondered anyway.
2) If there is no interview, I'm curious how do you go with a picture update on a TTP card? I tried tapping on "Replace Card" button in my TTP screen and it looks like the only reasons listed there are lost card, damaged card or a name change. Not the biggest issue for most grown-ups, I think, but being 10 now he doesn't really look a lot like he looked at 5. Is there any process of "updating" a picture? Should we just walk-in to any enrollment office when we have a chance and ask them to re-take a picture?

Thanks!