I want to link the newly created issues to the existing with the same "Summary" by transition. I’ve tried with your description for Create issue link for Jira Workflow Toolbox post-functions, but can’t find the right settings. Hope you can give me advise.
You should use post-function Create issue link with the following configuration:
JQL Query used is:
summary ~ "%{00000}"
If you want to restrict issues within the same project use the following JQL query:
summary ~ "%{00000}" and project = "%{00018}"
Note that:
Once configured, transition "Create Issue" will look like this: