There are a lot of very intimate pictures of Carl and Ellie throughout Up. What I want to know is who took all of these pictures? They didn’t have any children, and we didn’t see any other relatives hanging around the house. Who could it be?
Perhaps a professional did some of them, or a family member. It’s also possible that they set the camera so it would automatically take the photo in around 10 secs, allowing them to do it alone.
When it comes to montages, I feel that just because they didn’t show something, doesn’t mean it didn’t happen. It’s very possible that a family member was visiting them, and wound up taking a photo of them.
However, [spoil]it’s possible that no family member took them, and Bryko’s suggestion is true. It just comes off to me that maybe Carl and Ellie grew out of contact with their family after so long, particularly since Carl is alone at Ellie’s funeral. (Or maybe he stayed after everyone left?)[/spoil]
Hard to know when it comes to things like this, so many possibilities. Maybe a feature on the DVD/Blu-Ray explains it. Fun to speculate though. 
Mykonos_Fan, about the funeral, [spoil]I think Carl did stay long after everyone else was gone.[/spoil]
My guess is that some of the photos probably were “set the timer and smile,” and some were taken by friends or relatives. Before the high-rise development took over, Carl & Ellie probably lived in a nice little area of houses with lots of friends and neighbors around.
Unless I’ve missed something, I don’t think there was any discussion of this on the Blu-Ray materials, though.