Eastenders - Stacey and Mo

[MiaWallace]

Why does Stacey call Mo nan?

Stacey's father was Charlie's brother.
Mo is Charlie's mother-in-law

So why does Stacey call her nan?

She did used to call her Mo I think.
Perhaps she just calls her it, like my mum calls her father in law "dad".

I guess so

thanks