My kids father left when they were under a year old. We haven't spoken nor has he seen them in over 4 years. He has been paying child support which I rely on but wants nothing to do with us. I would like my kids last name changed legally but still collect child support. My son is in school and are calling him but my ex last name and my children do not know my current husband is not there real father. The school will not do anything until I change it legally please help/