Thomas Welsh married Isabella Allan Rolley at Dundonald, Ayrshire in 1893. [Obviously Rolley or Rollo may well be the same person].
1901 census at 33 Forth View, Inveresk & Musselburgh, Midlothian.
Thomas Welsh, 33, Electrician, b1868 Ireland
Isabella A.R. Welsh, 31, wife, b 1870 Dundonald, Ayrshire
Maggie A Welsh, 7, dau, b 1894 Dundonald, Ayrshire
William F Welsh, 6, son, b 1895 Dundonald, ayrshire
Mary A Welsh, 5, dau, b 1896 Dundonald, Ayrshire
Annie I.D. welsh, 3, dau, b 1898 Dundonald, Ayrshire
Helen Welsh, 2, dau, b Dundonald, Ayrshire
Isabella A Welsh, 1, dau, b Dundonald, Ayrshire.
1911 census. I didn't open this. It is only on Scotlands People, so is not free. However, by the studying the Census certificate numbers, I can tell that all the undernoted people were living in the same house...
St Quinox, Ayr
Thomas Welsh, 42
Isabella, 40
William J, 16
Annie Jane, 13
Helen, 12
Isabella, 11
Elizabeth, 9
Thomas, 7
Robert, 5
May, 2
A lot of the names mentioned in the original post are here. I know you have the 1901 information already but it is handy to compare the 1901 with the 1911 as a way of proving that these two censuses are the same family.