Thank you Sue and also S. Sheard.
Sue is correct about the 3 sons and only 1 travelling to OZZ.
Sarah was convicted of receiving £34 stolen by her son Thomas who was also transported.
This is why I have reasoned that 1 came to OZZ and one was left behind. Thomas was transported on a separate vesel and perhaps I should have noted this.
The Marriage of Andrew in 1841 took place with the permission of his guardian William QUAYLE which suggests birth C 1821. Like the James you have noted later census info states he was born in Ireland.
James' birth would hasve been C 1828 and I have found a likely dissenter Baptism on the IoM in 1826 of Sarah daughter of Michael LYNCHY and Sarah Mullen.
Sarah is stated to be a widow on her entry on the convict indent.
The indent referring to Thomas referrs to a tattoo including "brother James".
My GG granddaughter Mary Ann, one of the 2 girls who came with their mother, has stated on her death certificate (Sydney 1901) that her father was James LYNCH an army officer.
Other documents here state that Mary Ann's maiden name was LYNCHEY.
I appreciate all the feed back I have been receiving.