Need help getting a step-parent adoption

Hello My husband and I have been wanting to go through with him adopted my two oldest kids. We have been married for 7 years. Im not sure where to start. My kids where born in Ar, but we are currently living in Hi. Do you go though Ar or Hi to get it started. My husband is in the military. My oldest dose know her dad and has seen him 3 times in the 12 years of her life. He dose not call or send anything and dosent pay child support. He is also not on the birth certificate. The only times she has seen her is when i have gone to visit my family that lives not to far from him. My second oldest has see his father when he was one day old if you can say that even counts. He has not been in the pic at all and dont know where he is. have an idea but dont know for sure. My son dosnt know that he even has another father. My husband has been fully supporting them for the past 7 years of their lives. we have two other children and the older two want to share the same last name for the rest of the family. the oldest have my madian name. Is there an easier cheaper way then going though lawyers? If any one can give me any info on where to start or any thing I would be greatful. Thanks Dinia