Hi The_Hooded_Claw,
I have been spending some time sorting out my notes, and think I have quite a lot about your family - possibly going back several generations (at least 3), but obviously this is very tentative, and would be subject to having more info to confirm this or otherwise.
If I am correct then actually Sandy was married to Mary (not Agnes) and three of the children they had were Willliam J (who I think was your James, and there is some evidence to support this), b 1907, Rosanna, b c 1909, and Thomas b c 1910.
Work now takes me away for a week or so, but hope to find a message from you on my return.