How long are you going to be in Sweden? Unless things are different in her country of residence, as a U.S. Citizen it was quite easy for me to go by one name or the other for a couple of months, until I got all my records sorted with social security, banks, passport, etc. I used whatever matched the appropriate document at the time. Would it hurt for her to fly back under her maiden name? Is her photo ID and passport already going to be changed with the married name somehow while you're in Sweden?