In'my adopted family novel', the main character is most likely the one who has been adopted. This person's journey of fitting into the new family is the main focus. However, the adoptive family members are equally important main characters. The mother and father in the adoptive family, who may have different parenting styles. And if there are siblings, they too are main characters as they contribute to the family environment and the adoptee's experience within it.
The main characters are often the ones directly involved in the adoption process. So, the adoptee is a key character. They might be a child or even an older person who is being adopted. The adoptive parents are also main characters. They have their own personalities, motives, and backstories that influence how they interact with the adoptee. And don't forget about any extended family members that might be part of the story. They can have a significant impact on the adopted family's life and the story as a whole.