And yes it is possible for him to get rights (if your fiance and her ex are NOT married). Being a tier II sex offender does not immediately terminate his rights -- not all tier II sex offenders are pedophiles. And bieng a pedophile does NOT necessarily mean he will receive no rights.
Parents should remember 3 things: Love your kids more than you hate your ex; when you have children the relationship with the other parent is until death; your children determine what type of nursing home you end up in.
Nothing stated by me should be taken as giving you legal advice or forming an attorney/client relationship.
Attorney-GAL in Ohio.
I've removed the knife from my back, polished it, and will one day return it -- long after you think I have forgotten.