She is your step mother not your biological mother

no deed of adoption has been executed 

Law does not recognise her as your mother 

Hello, 

1. I suppose your birth certificate may have p your deceased mother's name as that cannot get changed. 
2. As your passport has your step mother's name you would not have much difficulty in getting a declaratory order from a court in India that she is your legal parent. 
3. You will need to produce her marriage certificate, death certificates of your decreed farther and mother and your birth certificate and move an application though your lawyer in the district court where your step mother is currently residing. 

There is actually no legal relationship between a step son and step mother unless adoption is done. Which means one of the biological parent should give consent for adoption of his/ her son or daughter.

You can apply to court seeking a declaration that your step mother be declared as natural  guardian stating that facts of she brought up you under her care and guidance. 

Court would not pronounce your step mother as your parent 

she is your step mother legally .

had you been adopted then her name would have been reflected as your adoptive mother 

Point is here neither of your biological parents gave consent for adoption. 

Without adoption no legal relationship will establish. 

Applying court stating the facts and circumstances of your step mother brought up you to declare a natural guardian for you if you want  to name  your step mother as your guardian. 

She can not be declared as your step mother without a valid adoption. 

Hello, 

1. The document as mentioned would be a declaratory Order of the court clarifying that your step mother is your legal and surviving patent. 
2. It depends on where you need to prove the relationship on record. It will be valid before any authority governmental or otherwise. The fact is that the court, legal authority has ascertained facts and certified the truth of them. 

Adoption deed cannot be backdated 

adoption deed has to be signed by biological and adoptive parents 

there has to be giving and taking ceremony 

Since both your biological parents are not alive,  this relationship will remain formal with no legal sanction. Neither of you and your so called formal step mother shall be legally liable to each other except for natural love and affection. 

I already advised you to apply court stating the facts of your step mother brought up you under her care and guidance, to declare her as your natural guardian.

Law is totally silent on this issue. What I am telling you that are the views taken by different court including High Court. 

You can on basis of birth certificate change your mother name in passport and other documents to reflect your biological mother name 

Step mother becomes guardian by way of her marriage to your father.

However you have no right to her  property unless you are legally adopted. If your deceased father had property You have property rights along with your step mother and other siblings of yours if any, inclusive of step brother or sister.

Coming to the documents which already made doesn't have to be changed and and there is already her name appears as mother. It's up to you and her if you want to change. Your step mother will not be legally your mother even if there is legal adoption deed . But if you want to support the documents which are with your step mother's name as your mother,an adoption deed will not help as adoptive mother can't become biological mother.

Before the technical purpose as per your documents she is your mother. Since you don't have birth certificate issued no mismatch or contradiction can be brought out legally in terms of documents. 

Your step mother cannot become your biological mother neither she can become your adoptive mother without having legally adopted you by observing the legal formalities.

The name of your step mother being recorded as mother in the passport of any other document shall not be legally proper or right to mention her as your biological mother, especially when your birth certificate has the name of your original biological mother recorded in it.

Therefore no court shall grant her the status of your adoptive mother without a registered  adoption deed 

The opinion you seek about the category of of your step mother ?

Even by producing your biological mother's death certificate or your birth certificate or the evidence of your step mother's marriage with your deceased father shall confirm that she is your step mother only and not an adoptive mother.

An adoption deed cannot be executed now on a backdate.

Since your biological parents are not living anymore, nobody can give you in adoption to your step mother.

Adoption can be only for child and not for adult.

If you are 18 years or above, old, then there can be no adoption done at this age. 

You can remain as a step child to your step mother. 

You pretty well know that the name of your mother in the existing documents are incorrect and it is not true, hence you need to amend or rectify the same by following the name change procedure.

If your birth certificate has your original mother i.e., your biological mother's name, that can be used as a documentary proof to change your mother's name in all those documents where your step mother's name has been recorded as your mother.

She needs to execute adoption deed in the said circumstances