Graylady
As with everyone else I have not found any documentary evidence of your William Hotson born 1820. However . . .
All the other bits of information do fit a particular Hotson I know of.
As a rule the Hotsons were a Langholm family.
Alexander Hotson did marry Grizzel Nichol. They married in 1803.
Alexander had a sister Mary who married James Beattie. a tailor.
Alexander and Grizzel had several children. I have a record of 12.
Their eldest William baptised in February 1803 was William. "His son went to South Africa and later to Australia'
John baptised in 1810 married in 1842 in canonbie and went to Canada in 1853.
Walter baptised in 1813 married in Langholm and went to Harriston, Ontario.
Margaret born in 1816 married William Beattie 1846 in Langholm and went to Canada.
James Simeon baptised in 1817. He went to canad and married there.
A younger brother Alexander baptised in 1822 married in Canonbie and went to Canada in 1851.
The next and youngest son George was baptised in 1824, went to Canada in 1849 and married at Innerkip in 1851.
The information is from details a contact gave me.
No William apart from the eldest is noted.
Everthing else apparently fits.
Do let me know if this helps anymore. Alexander and Grizzel's photographs are in a book written by. I think, a nephew
Regards
Reiver (Beattie)