I wrote a big Google Doc, soon to be published on CodingSight, about doing WordPress database merges - necessary when a staging site and the live site are running in parallel.
There are some new records on live and some new records on Staging, and a few new updates to existng articles on Live...so I will have to bump up some of the IDs because some of them are the same because the two sites were expanding at the same time. I have a powerful database comparison and update tool for doing the actual updates.
As I am bumping/incrementing the IDs, like by 1000, up to avoid the collisions, there are a few cases where I have to run 3 queries, rather than having On Cascade Update, because MyISAM does not support referential integrity. Think Posts and Postmeta or Woo Orders in Posts and the related WooCommerce tables.
Looking for someone with the actual skills and literacy to read my document, and extract the relationships between tables based on my queries, check for omissions, and deliver me a documented script to modify my database and then reverse those modifications, so that I can run just one update query on the main table, and have the downstream updates run automatically.
For example, I see posts to term_relationships, posts to postmeta, users to comments, users to usermeta, users to posts, posts to comments, where updates to the keys should cascade.
This site has WooCommerce, too, so want to put integrity on the WooCommerce tables like Orders as well.
In your proposal, explain why there are data collisions in posts in the scenario I described, and at least one pair of tables that should properly have referential integrity, and what change is required to the database tables.