Hi Jean,
I've got an index for 1841. I'll have a look.
There is no guarantee that the family are together the ages in 1841 are a bit older.
There are 2 David Thomsons in Dumfries both are 2 young I'm afraid.
One David was 22 a cotton hand loom weaver Ed: 19 p:16 Brasswell.
Other people in this household with name Thomson are Margaret age 60, Jannet age 30 ag lab,
The other David was 25 a joiner ED:9 p:17 Friar's Vennel.
Other people in this household with name Thomson are Margaret age 45, James 20 a cabinet journeyman, John 50 grocer & publican, Robert 13, William 16.
So assuming David may be dead or away looking for Jan(n)ets of the right age.
There is one age 60 at Castle St ED:6 p:9. She is born in Scotland but outside of the county.
Other people in this household with name Thomson are Alexander 20 born outside county, James 60 writer born outside county, Jessie 20 born outside county.
Moving through the children. Was Henrietta really married at 13?
Who did she marry I could look for her in 1841 if I had the new surname.
There are no Martha Thomsons.
Two Robert's of interest.
One Robert age 18 a tinsmith App. at Loreburn Street ED: 7 p:26.
Other people in this household with name Thomson are Jannet 10, Margaret 2, Rebbecca 40 bn Ireland.
The other Robert age 20 ag servant Carthajenia ED: 18 p: 2
No other people in this household with name Thomson.
The only William of the right age is the one mentioned above at Friar's Vennel.
There are a few Mary's and Janets but they are in houses with different apparent parents.
Sorry I couldn't find them
If you give me the married name of Henrietta I'll look for her.
Cheers,
Pam