Hello @Nagaraja
Are you asking for someone here to build a new feature into Jira’s REST API to meet your requirements? If so, suggestions for new features for Jira are raised through JAC in the Jira Cloud section.
If you are asking “Does an endpoint for bulk adding comments to an Issue exist?” then the answer is the same as this question you asked last week about bulk adding attachments to an Issue… Nope, you must add them one at at time.
If you Google ‘Jira Cloud REST API bulk add comments to an issue’ or ‘Jira Cloud REST API bulk update an issue’ you’ll see many threads in various places where that question has been asked before.
Broadly speaking, the functionality of the REST API endpoints is described in the documentation. If you can’t find any endpoint that has the functionality you’d like, then it’s reasonable to assume it doesn’t exist… so you must find if a matching suggestion for such a feature has already been raised in JAC and vote for it, or create the suggestion for that feature yourself.
I notice you keep using the word ‘we’ in your questions, so I assume you’re part of a larger development team responsible for this activity. Surely someone in the team must have come to the conclusion that you’re embarking on a huge cost and effort activity compared to just buying a fully functional, off-the-shelf solution. Third party add-ons for syncing issues between Jira instances are available in the marketplace for reasonable prices, so its strange that you’ve decided to re-invent the proverbial wheel yourself.