When they both entered the house we could already sense they knew each other, but as I read on the train in the daily mirror Nikki and Grace's mothers have revealed THEY KNEW EACH OTHER BEFORE BIG BROTHER!
They both worked in Harrods together and then one of them left and they never spoke to each other.
So before big brother Grace and Nikki worked together, as told to us by their parents in the daily mirror.
A bit of a coincidence lol, they are keeping it a secret I think!