Douglas McGuire - a man of many numbers

This search really had me stumped for a while. Firstly, to correctly identify who I was looking for and then to locate the family.
I was contacted last week by Jim T in WA and he provided the naming on a medal as WP37316 D.G. McGuire. This threw me a bit as the service number didn't give me a hit in the WWII nominal roll. I know there are some different letter and number combinations beyond the usual state/militia/2nd AIF/service arrangements but this was really strange.
The only D.G. McGuire who came close to fitting the bill was Douglas George McGuire. The nominal roll entry shows two numbers; 5400 and WX30146. The 5400 number immediately suggested a post WW2 number issued after the Australian Regular Army was formed in September 1947. So I was looking for a soldier who continued to serve but I needed to confirm the link to the name on the medal.
I followed Douglas to his death in 2009 and instantly hit another hurdle. His name was spelt differently - this time MacGuire. So it was back to the start and it was then I confirmed it was the same person. I found records showing that Douglas George MacGuire was born on the same date and in the same location as the Douglas George McGuire on the nominal roll. There must have been a period where Douglas had another number altogether and this is the one on the medal.
Following WWII, Douglas and his wife were posted several times to Ammunition Depots in different states. They spent some time in Albury, NSW and then at Northam in WA. Douglas took discharge in the mid 1960s and they settled in WA. However, not long after this I lost all track of Douglas and his wife, Zelma, until the details I found out about his death. So I turned to his wife.
I found a 1952 death notice for a lady who died in Rockingham, WA which mentioned her grand daughter, Zelma and her fiancée Doug McGuire of Northam. Bingo. Other death notices game me the names of Zelma's siblings. After a couple of false starts I focused on one sister who had an unusual initial-surname combination. After checking the details in the electoral rolls I looked up the name in the White Pages and sure enough there was the same initial-surname combination listed. I took another punt and was soon talking to Zelma's sister.
From her I learned that Zelma and Douglas divorced and she had remarried. The best news was that Zelma is still alive but now goes by the name Thelma. I don't think I would ever have worked that out using the electoral rolls. I've since spoke to Thelma and I'll send her the medal soon, she is then going to pass it to her and Douglas' daughters.
Thanks Jim.
The retuned medal tally is now 1251.