You have information on Thomas McCracken death and burial so the next step should be to contact the cemetery and find out what information they can give you. The cemeteries often have a lot of information in their files. You can also contact the Vancouver Public Library and ask for an obituary look-up as you have the date of his death. That may give you the names of his children. Also go to the Canada 411 site and look up the name McCracken on the directory and then sent off a letter through snail mail to the ones that look promising. Doing these things may give you a lot of information without spending a great deal of money.
For Robert McCracken, order his military file. I have just gone through some files that I have on my relatives and this is some of the informtion you may get.
1.Attestation papers
2.Particulars of Family of an Officer or Man Enlisted
3.Separation and Assigned Pay Branch documents - Pay sheets will show if he assigned any of his pay and to who. Also will show which battalions he was with when he was paid and if he was in the field at the time.
4.Documents showing his theatre of service, unit and dates
5.Casualty Form Active Service - will show when he was injured, what hospitals he was in and the dates, his injuries and also whether he was able to recover from the injuries or if he was permanently disabled.
6.Dental certificate for demobilization
7. Medical Examination Upon Leaving the Service
8. Examinations
9. Medical History Sheet
10. Records that show his return to Canada, dates and ship
11. Discharge Certificate
12. Record of Promotions, reductions, transfers, casualties, during active service
13. Proceedings on Discharge - This sheet actually will give the proposed residence after discharge and this could be very valuable in your search for Robert. Also on this sheet on one of my documents the death date is written in.
The files that I have ordered each contained around 40 pages and had information that I was able to use to fill in a lot of gaps. If Robert was injured as severely as you think there should be followup information in his military files.
If you know the unit and date that Robert was injured, you can go to the war diaries and find the battle he was injured at.
You can also do a search for the Last Post Fund. This fund has been used to help pay for headstones of military service personnel that don't have a headstone. They may have a contact section and be able to help you.