• From December 3, 2004, onwards, a person born outside India shall not be a citizen of India by descent, unless his/her birth is registered at an Indian consulate within one year of the date of birth or with the permission of the Central Government, after the expiry of the said period. 
• An application, for registration of the birth of a minor child, to an Indian consulate shall be accompanied by an undertaking in writing from the parents of such minor child that he/she does not hold the passport of another country.
• Further, a minor who is a citizen of India by virtue of descent and is also a citizen of any other country shall cease to be a citizen if he/she does not renounce the citizenship or nationality of another country within six months of attaining full age.
• The citizenship of minor children of persons who are citizens of India can be got through registration by an application to the Central Government. 

Further Reading:

• Pravasi Bharatiya Divas
• Difference Between NRI and PIO
• Citizenship Amendment Act 2019 (CAA)