Per the Douglas Borough Burial Register
Jane Welsh bur 1942 was 68yrs this would make her born in 1874
I don't see any other Jane Welsh or Welch in IOM burials

Joseph Welsh bur 1964 was 83 si born 1881 so he might be the right one. I checked the MI for NN 162 which index says is where he is buried--however he isn't listed in the inscription
Rather Robert Christian died 7th Dec 1960 aged 62 yrs
Ida May died 9th Jan 1982 aged 76 yrs
*********
As I believe you know,a JJ Christian and J Criggal actually were married
CHRISTIAN, John James Clark 16 Sep 1886 R A1 36 CRIGGALL, Jane

Lezayre New West Yard
A 84/A 86
Sacred to the memory of John James Christian plasterer born 21st December 1852 died 4th July 1928
and Jane his dearly loved wife born 5th January 1863 died 8th November 1934
Frederick their dearly loved son born 18th July 1890 died 20th July 1951
Myra their dearly loved daughter born 24th May 1887 died 13th February 1955
Annie their dearly loved daughter born 11th January 1885 died 14th September 1962
Lena their dearly loved daughter died 5th October 1969 aged 70 years