STEVENSON - Minnigaff

[snowwhite77]

Looking for further info re Andrew STEVENSON born around 1811/13 Minnigaff.
He married Janet MORRISON  23rd June 1839 Penninghame.

Have details of him from census' giving me childrens names etc..

I have also found Andrew's death which states he was iligitimate and mothers name Janet McMILLAN. Andrew died 27th Nov 1877, near his house in Newton Stewart aged 66. The informant was his son George. (His wifes address on 1881 census was 31 arthur St Penninghame.)
In margin is note containing reference to the Register of Corrected Entries(RCE) for 7th Aug 1878, result of precognition. The major part of the note cannot be read. 

Can anyone help me find anything further,
I have wondered why his surname was Stevenson while his mother was unmarried. I have treid looking for a marriage between Janet and a STEVENSON thinking he perhaps took his step fathers name.
Any help appreciated
Amanda