Claiming Child

My husband and I have guardianship of a child that was born last July. We are applying for the plenary guardianship this year. He has been with us since he was born. Can we claim him as our child? The mom did not want him and we are solely raising him. We went along this route due to the length in time we had between finding out and his birth. He lives with us full time and all his needs are provided by us.