If you need to order your posts by metafield set up in Relations Meta, please, follow these steps:
1) Firstly, create an SQL query to pull the table that contains the relation meta field. For example
2) Proceed to Where (query clauses): here, we need to pull the posts that meet several conditions: a) they contain the same meta key; b) their parent_object_id equals the current post id
Example (listing of children is located on the Single Post page of the parent post):
3) Configure the ordering parameters:
Save the query.
4) Create another custom query - Posts Query type. Proceed to the "Post & Page" tab and use the "Query Results" macro on the Post In field:
5) Return to the "General" tab and configure ordering parameters:
6) Finally, apply the query to the listing:
