Heather, not sure where you are based...
Regarding the question marks on the family through the 1890s, poor relief application records may be your way forward. These provide unique information, not available elsewhere. They are only available to view/search for in person at the Mitchell Library in Glasgow.
1901 here, for background to this post. Guess Joseph shows as a widower on the original image?:
Margaret Buchanan 38 Cookery Assistant Public School b. Glasgow
James Buchanan 14
William Buchanan 17
Margaret Dias 67 mother b. Glasgow
Joseph Dias 40 brother butcher b. Glasgow
Isabella Dias 10 niece b. Glasgow
Address: 5 King Street, Glasgow/Calton
A short film here on what is available, from youtube -
www.youtube.com/watch?v=ew5Le5QpKxk&index=15&list=PLsH04lz042gczqH-IOL3upZKJ9f1Ahu1Q This is Part 6. Part 5 is the other one that is relevant for Poor Relief Apps, see
www.rootschat.com/forum/index.php/topic,522720.0.html for summary of all the films - Part 5 now available here,
www.youtube.com/watch?v=a3gynoyk05QMonica
