changing childrens last name after divorce

i am very curious about massachusetts law about changing your childrens last name with out the need of the non custodial parents consent.i read it on some web site.my children have no contact with thier biological father.both of my children wish to change thier last name to my now current husbands last name.bio/father has no contact with children no visitation rights as of day i went to court for divorce.drugs and alcohol is his only concern.i believe always has been.i believe it would hurt my children if they were to have any contact with him at all.i made a very bad choice when i married him or even dated him,i know what people say about children needing their fathers . believe me i agree. i know what it was like growing up with out mine.my husband now loves my children very much . and has for 9 years.so please can some one give me some infior about changing my childrens last name without the consent of the non custodial parent? and also what is the difference between that changing of name and my husband adopting them thank you very much?