Help & Advice how i can change my 2 kids last name ( father's last name) who's not giving any financial support anf we havent see him in 3 years already, into my husbands last name

Hi, I just wanna know how i can change my to kids last name, my 2 kids father was my live in partner before and their last name is their father's last name. Now Im already married with someone and i want to change my 2 kids lasy name to my husbands last name. I dont know what steps to do, coz i havent seen and talk to my kids father for 3 years cause i dont know where they live because and they dont have any permanent address they always move to different apartments. im still having doubts to talk to him cause i had trauma because before when were leaving together i was physically & mentally abuse by the father of my kids. I want me & my kids life to be peaceful already i hope you can help me. Thank you

You and your husband can adopt the 2 kids