The Export and Import for Storefront overlays will export or import all overlays for both Parent and Child products. This means you can export and import once and cover all your products with overlays.
Find the Export and Import: EvoX Admin => Products
Anatomy of the Import
The first 3 columns represent the product record that the overlay is assigned.
Parent and Child products
If you have a Parent product with 2 Child products, you will have 3 separate rows to represent each product record that has an assigned overlay
The "New" named columns represent the overlay data you want the customer to see. You can fill out as many columns as you need. When a column is left empty the product record data will be shown to the customers on the storefront, instead of the overlay.