Astrid Helene Johnsen

I am trying to verify a theory on: Astrid Helene Johnsen b. 25 July 1909 in Christiana daughter of Karl Marentius Johnsen and Anna Fredrikke Iversen I have not been able to locate a marriage record for Astrid - but I did a search of Oslo cemeteries (which a very nice member taught me the trick a week or so ago - Thanks!) and I find an Astrid Helene Smith born the same day and died in 1995. She is buried with a Sverre Smith - which would probably be her husband. How can I prove this is the same Astrid Helene? How about finding if they had children? Thanks for any help or clues you can give me!