First of all I would like to thank you guys for putting in so much effort and coming up with great information. I haven't had the internet for over 2 months so I haven't been able to look at the thread.
I've had a few hours and I'd come up with a great theory and then had it blown out of the water haha!
The hubby will be watching the world cup tomorrow so it should give me plenty of time to do more research. In the meantime I'll tell you my theory and then one or two extra bits were found that confuse it all.
Ok, so when Mary Ann Brown was found living with Elizabeth I thought that Mary Ann nee Sullivan was living with her mother in law after both their husbands died (Elizabeth is listed as a widow and it looks like "" is done below it on Mary Ann's section too suggesting she was also widowed). Alvaretta being her daughter and the other children belonging to Elizabeth. I thought that possibly she was staying with them, but had recently been married to George Martin, which was why she turned up in both households and why she was scribbled out of Elizabeth's household.
I searched some of Elizabeth's children and found that Susan married James Sullivan(!) in 1871. Her marriage cert confirmed her parents were Matthew and Elizabeth Brown. I couldn't find anything on the other children.
As someone correctly mentioned, this Mary Ann Brown married a George Fox. At first I thought this must have been another Mary Ann Brown of the same age, but on the marriage certificate she lists her parents as Elizabeth and Matthew Brown. So it is definitely her. There is no record of a George or Mary Ann Fox on the 1871 or 1881 census, but also no death for George either.
Now here is where is gets really interesting - the witnesses to Mary Ann Brown and George Fox's marriage were Susan Brown and George Martin!
So my theory that Mary Ann was born a Sullivan, married a Brown, was widowed and married George Martin has been blown out of the water.
Now it looks like Mary Ann was always a Brown, married a Fox, had children living with her (her's out of wedlock, someone else's that she's adopted) and is married to a Martin.
Or they are two completely separate people who's lives are entwined by similar dates and names. But that seems unlikely somehow.
But if they are the same person, where have the children come from (both James and Alveretta would have been born before her marriage to George Fox) and where has the name Sullivan come from.
Or I could be going off in completely the wrong direction and missing something.
I'll be at it again tomorrow (I hope!). In the meantime, any more theories?