Around 2014 I read a short story collection; in the collection there was a story about a futuristic world where people had nanny bots to look after and entertain their children. In the story a nanny bot breaks down and I remember something about a box with the new nanny in showing up and them assembling it.
I do not know very much more of this story, other then the plot-twist:
as it turns out their kid is also a robot they bought.
As it is a memory of long ago the details of the story I provided can be faulty but I am sure of the twist.
What story is this? Would love to find and read the collection again
It is not Nanny (1955) by Philip K. Dick, as answered below. It is not Supertoys Last All Summer Long by Brian Aldiss,as answered below.