Section 6. If the court is satisfied of the identity and relations of the persons, and that the petitioner is of sufficient ability to bring up the child and provide suitable support and education for it, and that the child should be adopted, it shall make a decree, by which, except as regards succession to property, all rights, duties and other legal consequences of the natural relation of child and parent shall thereafter exist between the child and the petitioner and his kindred, and such rights, duties and legal consequences shall, except as regards marriage, incest or cohabitation, terminate between the child so adopted and his natural parents and kindred or any previous adopting parent; but such decree shall not place the adopting parent or adopted child in any relation to any person, except each other, different from that before existing as regards marriage, or as regards rape, incest or other sexual crime committed by either or both. The court may also decree such change of name as the petitioner may request. If the person so adopted is of full age, he shall not be freed by such decree from the obligations imposed by section six of chapter one hundred and seventeen and section twenty of chapter two hundred and seventy-three.

In evaluating whether a petitioner is of sufficient ability to provide suitable support for the child, the court shall give consideration to assurances by the department of children and families that it will provide an adoption subsidy for the child.

No decree shall be made under this section until there has been filed in the court a statement, signed and sworn to by the petitioner, or petitioners, setting forth the date of birth and place of residence of each adopting parent and such other facts relating to each such parent as would be required by section thirteen of chapter forty-six for the correction of the record of the birth of the person sought to be adopted, and also a copy of the birth record of such person; provided, that in case such person has been previously adopted, either a copy of the record of his birth amended to conform to the previous decree of adoption or a copy of such decree may be so filed; and, provided further, that the filing of any such copy may be dispensed with if the judge is satisfied that it cannot be obtained.

Every decree of adoption entered by the court shall include the words ''This adoption is final and irrevocable.''

The probate judge may determine that the hearing on any adoption petition shall be held in chambers. He shall, on the request of any party to an adoption proceeding, hold the hearing thereon in chambers, except that if said petition is contested, the consent of the other party or parties shall be required. No person shall be allowed to be present at any such hearing unless his presence is necessary either as a party or as a witness, and the probate judge shall exclude the general public from the hearing.