George Friend and Elizabeth had a daughter Sarah Ann Friend in 1874, she would have been Fanny's half sister. Have you researched her?
Looks like Sarah Anne died aged 6 just before 1881 census, so she can't be Mrs Jefferies.
George Friend was a widower when he married Elizabeth. Were their any daughters from first marriage or his later marriage to Alice? The term sister might be used loosely and Mrs Jefferies was actually a step sister
George Friend had been married to Fanny Wells before Elizabeth Farmer
As far as I am aware George and Fanny had 4 boys before Fanny's death
In George Friend and Alice née Stedman are in Forest Row with
George and Fanny's sons
James aged 17,
George 15,
Jesse 11
And
Charlotte Friend, dau, 4, although Charlotte was actually Alice's illegitimate child and registered as Stedman
And finally Alice and George's son
Frederick H aged 1
No sign of Fanny
But Maybe i should research Charlotte as being Mrs Jefferies