https://www.epo.org/en/service-support/faq/searching-patents/asian-patent-information/india/general-information-about-1
What are patents of addition in India?
Patents of addition relate to improvements in or modifications to patented inventions. A patent of addition cannot be granted before the main patent is granted. If the main patent is revoked, the patentee may request the conversion of the patent of addition into an independent patent. Patents of addition have the same term as patents for the main invention.
If you require a more detailed answer, please send us your question using the contact form.