You can use Jira Script Runner and modify the code shared by Henning here
I wrote a plugin to do this and it is available here
Please download and try it out and rate and review the plugin if you like it
Of course. I have a Post Function that does the following:
What I am looking for is a Post-Function that will be executed on IssueA that will copy the comments to the linked IssueB. Ideally being able to specify the "type of link" the connects the two issues would be great (since there are many different types of links).
Ideally this would have been done in the original 3rd Party plugin (Create on Transition -- https://marketplace.atlassian.com/plugins/org.swift.jira.cot), but they don't seem to be adding updates too often.
I hope that helps.