Have just found this 1901 which may be worth a look -
Hugh Horne 41 b. Croselos, Renfrewshire
Marion Horne 45 b. Kirkintilloch, Dumbartonshire
Hugh Horne son 12 b. Kirkintilloch, Dumbartonshire
Susan Horne dau 4 b. Bellshill, Lanarkshire
10 Muirhead St, Kirkintilloch, Dumbartonshire
I cannot find a birth for a Susan Horne and as Susan Coyle appears to be on the 1911 living in Kirkintilloch the above Susan could be Susan Coyle but under the family name of Horne. Perhaps Hugh and Marion Horne 'adopted' Susan.
All very speculative but worth considering.
JJ
Added Hugh's birth can be found under Hugh Horn, 1888, Kirkintilloch