Under the provisions of Section 5 of the Hindu Adoptions and Maintenance Act, 1956, no adoption can be made by or to a Hindu except in accordance with the provisions contained in the said Act, and any adoption made in contravention of the said provisions shall be void, which means of no legal effect. So, firstly check whether your adoption meets the mandatory requirements of the said Act. Consult a local lawyer if you are not able to do it yourself. If your adoption is not in accordance with the provisions of the said Act, then the adoption itself being void, there should be no problem if you use the name of your biological father.
However, if your adoption is legally valid under the provisions of the above Act, then please note that Section 12 of the said Act lays down that, “An adopted child shall be deemed to be the child of his or her adoptive father or mother for all purposes with effect from the date of the adoption and from such date all the ties of the child in the family of his or her birth shall be deemed to be severed and replaced by those created by the adoption in the adoptive family”. Therefore, in such a situation, it may not be legally permissible to use the name of your biological father as being your father, since you would be considered as child of your adoptive father and mother (nana and nani, respectively, in your case) for all purposes.
For your second question, appear in the court which issued the NBW (non-bailable warrant) and get the NBW cancelled by binding yourself for appearing on the designated dates in future. If needed, take your advocate with you when you appear in court.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.