Profile: Massimo Scalese

Problem:

The issue here is that the user wanted to list their child posts on their parent archive listing.

Solution:

To get this clear, you want to list out the parent post and their respective child posts under each parent like this.
Parent A
--Child 1
--Child 2
Parent B
-- Child 3
--Child 4

If that is the case then what you will need to do is to follow the instructions below.
1. Create a custom Archive for the Parent CPT by going to Toolset -> WordPress Archives.
2. Go to View->Add New and create a new view that will list the child post.
3. On the child post view you are going to add a query filter for the post relationship and set it up like my screenshot.
4. Go back to your custom archive and then add your child view to that custom archive.

Once you have done this your Archive should be listing out your posts in the example i've added above.