In the admin view -> Catalog -> Products, under main products there is a section Variations where all variations of main product are listed regardless of "Limited to store" products settings.
Variations can be added, edited, and deleted manually in the admin view.
When Edit is button is pushed then "Show in Product Details", "Show in Category view", "Display order" can be changed.
"Show in Product Details" has effect only in case in plugin settings "Show Product Variations Widget" is active.
It is possible to navigate to variation by pressing button "View".
When products are inserted to NOP then it is possible to define product as variation by choosing main product and adding id of the product that must be variation.
NB! Variation id is not sku but system id. System id can be found when in admin view opening product card and then in url Admin/Product/Edit/4.
In the admin view -> Catalog -> Products, under variation there is also a section Variations where main product is shown.
It is possible to navigate to main product by pressing button "View Main Product"
In admin view Catalog -> Products search options are complemented with 2 options:
Search if Main Product - in case chosen then search is done only main products
Search if Product Variation - in case chosen then search is done only variations
When both checkboxes are checked, then both main products and variations are returned
When both checkboxes are unchecked, then all products are returned (regular products as well)