Answer:
9 hours and 7 minutes
Explanation:
The son, born at 11:11, Kirtsy's daughter being born 111 minutes later would put her time of birth at 1:02. The final child (daughter) was born 111 minutes before midnight. putting her time of birth at 10:09. Take the time between the two and you get 9 hours and 7 minutes between the two girls.