Alice through 2nd floor window

[Rich3]

At the beginning of Little Big Man, Bobby is hanging at the window of the girls bedroom window and Greg saves him from inside. Meanwhile Alice has set the ladder up again and is now at the window herself.

There is a shot of the backyard area outside and below her.

If supposedly all the upstairs scenes were filmed from first floor sets, how was this shot accomplished then?

I'm suspicious of the claim that the filming location did not have an actual upstairs.