Sorry having trouble with the computer and only just got the last post in. Storms last night. Looking at you assumption for Mary's parents, why only her mother came as convict. her father could have and her mother came free with Mary and possibly other siblings. It's a fair guess they didn't just immigrate.
Mary Born roughly 1826 married in 1840 AGED 14!! Not impossible then but someone had to give permission. The wedding 1840, if it happened, has not been indexed, also not unusual.
It was not unusual also that the married couple Quinn lived together after arrival, so more children. There are only two couples on the index. A William Quinn or a James Quinn, both having children in the right timeframe. Neither couple's before 1830. James and Mary the earlier of the two with a birth 1832.
There are quite few deaths recorded of James Quinn as possible previous Prisoners, normally no parents shown at death on register, prior to 1860 and as early as 1844. Two deaths are doubled up on the registers but one in 1844 stands out. James Quinn aged 37 in 1844 Rf # V1844626 44B/1844
Neil