Now that we've created a metafield that links to our siblings metaobject, we can let each of our products know to use it.
Fortunately, Shopify has a bulk edit option in the product setup which makes this step very quick and simple.
Breakdown of steps covered in video
In the Shopify admin -> products, filter and find your sibling products
Select each of them. Then use the bulk edit button at the bottom.
Click on the columns button at the top to choose which columns are displayed. Uncheck as many as possible as you scroll through the list. When you reach the metafields section, choose the metafield we created in the last step (link to products).
For each of the products, click on the empty space under the link to products column. Click on the select entry button.
Choose the correct entry you created for the product list.
Repeat for each of the products in your siblings group.