No date, but like Gregor, I'm assuming these are later than the 'Sitting Bull backdrop' photos and not as late as those featuring the tipi backdrop, which Barry used to photograph the Second Sioux Commission against in 1888.
His wife
And again, this time with the garden furniture
Gall and his nephew. Note that although this must have been taken at the same session, there's a different backdrop! Maybe Barry's studio was big enough to have two. Significantly, this backdrop features in a number of other photos. The phony stone thing to the right is actually a seat.
Here they are with the seat turned around
The nephew dressed in the same clothing, with seat but against the other backdrop
With his wife and nephew before the other backdrop.
As you can see there are several slight variations on these poses - and there are others that I didn't post.