Well going by the inscription up to the word 'reunited'
maybe was the original time the headstone was erected about pre 1936 and daughters added as an after thought! especially the 1915 entry maybe placed as well in 1949 to put both sisters on the inscription?, then run out of room on the stone for Elsie or Edith inscriptions but without researching stonemason records it will will remain a mystery unfortunately. The Gorton cemetery grave records of dates of burials are the more accurate anyway - so your research was not in vain.
Dave
