Here is Christina's address in case you want to write.  It will be the same for her entire mission.  Mail should go through the US postal service because they will forward it.  Otherwise, it remains at the mission home until she goes in for meetings--which can take a long time for her to get it.
Sister Christina Rose Trickler
Minneapolis Minnesota Mission
5931 W 96th St
 Bloomington MN 55438-1715