Appsync query on relation child object

Question

I am in the situation of mutation to create relations on AWS AppSync

I have events in one table, comments in another. In my graphql events type I have a field for list of comments with its own resolver

I would like to know how I can request only events that have comments, in the same way.

My situation makes I need also to filter which events I want to show so I can not start by getting list of distinct events in the comment table.

I would not like if it can be avoided to create a pipeline with specific resolver, to avoid code duplication.

Code can be retrieved to the linked stackoverflow question.

Thank you for help