Complex sentence: Burtin's wife Hilde took advantage of this stall to write an urgent appeal to her cousin, Max Munk, in Maryland, asking him to sponsor the couple's immigration into the United States.
Split into simpler sentences: Burtin's wife Hilde took advantage of this stall to write an urgent request to her cousin, Max Munk, in Maryland. She had asked him to sponsor the couple's immigration into the United States.