You are on the right track with Lists. Don’t worry about the unique ids, bubble links things for you.
So … this works on Locations, rather than Posts, but the idea is exactly the same …
We have a Comment table, which also has the parent Location.
And we have the Location table, which has a list of Comments.
To make the LISt you tick the box …
The way you handle lists is slightly different in a workflow, so you create the comment (and I refer it back to the parent location for ease) …
And then ADD the comment to the location.
You can then have a RG of Locations, each with an RG of Comments.
