I have some relatives whose bodies never seem to have made it to burial.

They all died around the same time and should appear in the burial records for the Catholic cemetery, which would be St Joseph's, Airdrie. The local cemetery office can find no record of them either there, or the other cemetery which would be Old Monkland, Coatbridge. I have all the death register records, all died in Coatbridge - but where else would they have been buried? The family lived in Coatbridge and I'm fairley sure they were not cremated but how do I find out?
They were;
Husband - My Great Grandfather
James Miller/Millar died 12 August 1911 aged 40
Wife - My Great Grandmother
Mary Campbell Miller/Millar died 21 June 1914 aged 46
Daughter - My Great Aunt
Rose Miller/Millar died 18 November 1918 aged 20
Another daughter died aged 2, in 1902 and I found her in the Stillborn/Infant section of Monklands Cemetery without a problem.
I'd appreciate any help anyone could give.
Regards
Gerry