Give the baby your last name and do Dna tests to determine who is the father. That is the responsible thing to do. If after all that the dude that is in jail gets out and wants to adopt the baby then go through the proper steps of having him adopt your baby.
girl i think its nothing wrong with him giving the baby his last name .. if he agrees and its okay with it then go for it ! goodluck and congrats btw :)
I would say give the baby your last name . By what you're posting it doesn't look like your stable and change your mind or whatever.... if when the guy gets out of prison and wants to be the father to your child he can have the option to adopt. You wouldn't want him leaving you and your baby is stuck with his last name..
I do not think you should do that, think about the baby in this and give the baby YOUR last name. Geesh