What is the procedure for valid adoption?

"Indian citizens who are Hindus, Jains, Sikhs, or Buddhists are allowed to formally adopt a child. The adoption is under the Hindu Adoption and Maintenance Act of 1956. Under this act, a single parent or married couple are not permitted to adopt more than one child of the same sex. Foreign citizens, NRIs, and those Indian nationals who are Muslims, Parsis, Christians or Jews are subject to the Guardian and Wards Act of 1890. Under this act, the adoptive parent is only the guardian of the child until she reaches 18 years of age. 
The Prospective Adoptive Parents (PAPs) should produce following original documents along with two copies on which self attestation is done for undergoing a legal adoption procedure.
1) Any of the following documents as Identity Proof – Pan Card/Passport/Voter Card/Driving License.
2) Address Proof - for example, any of the documents like Ration Card/Aadhar Card/ Electricity Bill etc.
3) Certificate of Marriage
4) The Prospective Adoptive Parents should obtain a Health Certificate from a registered medical practitioner stating that they are not coping with any incurable or contagious diseases or any mental or physical condition due to which they would prove incompetent to take care of the adopted child.
5) A Family Photograph.
6) Recently clicked Photographs of the Adoptive Family (three photographs of postcard size).
7) The self-employed Prospective Adoptive Parents need to furnish an IT Statement for the preceding three years. They have to provide an Income Certificate in case if they are employed in any organisation from that particular organisation along with the date of superannuation.
8) Two Letters of Recommendation are required to be furnished by Prospective Adoptive Parents. These letters of recommendation should be from the persons who are well acquainted with adoptive family and who are not the immediate relatives of any of the any of the Prospective Adoptive Parents.
9) Prospective Adoptive Parents also need submit Financial Statement which should include bank statements for preceding six months, particulars of loans taken and complete details of the moveable and immovable properties owned by them.
10) In case of previous adoption the Prospective Adoptive Parents have to furnish Adoption Decree.
11) If Prospective Adoptive Parents already have a biological or adopted children or child whose age is more than 7 years, they need to take Written Consent from such children or child.
12) Single Prospective Adoptive parents need to provide a Letter From a Close Relative stating that the relative would take care of child in case if any unforeseen circumstances take place.
13) In case of Divorcees (Single Prospective Adoptive Parent), Divorce or Legal Separation Decree needs to be submitted."