There are four main components to setting up product siblings:
Creating individual products. Each product can have variants like sizes.
Group the siblings products into a collection.
Define two custom metafields to link each product together which will automatically create linked product swatches.
Update the metafield information for each product.
Create individual products that are similar. Use the same name for the product title with each product:
Once connected to each other as siblings, they will appear with linked swatches to each other:
Each product can have its own images, inventory, prices, description, variants like Size:
A Color variant isn't required as that will be replaced by image swatches and a metafield is used to display the color.
Tip: Create the first product with sizes and prices, then duplicate that product and add new images for each variation and adjust the description, inventory, and prices. Only the product name needs to be the same for all products.
Collection for siblings
After creating the products, place them all in one collection. The collection does not need to be used for any other purpose:
The next step is to create two product metafields which are used to connect all the products and information together: