Should I let her Go To Oklahoma?

My G/F wants to go to Oklahoma to see her Father, Please do for as long as you want, but we have a 17 month old Daughter she wants to take with her, there is one problem with this, her father is a convicted child molester and hasn't registered in 8 years since moving there, we have joint legal everything is split right down the center as close as we could through the courts and I have major trust issues with baby's mother, Don't know if i should fight this or let her go, I miss my baby so much just going to work for the day it will drive me crazy not seeing her for two weeks Mery X-Mas everyone From California