Linking alternative products using metafields in Shopify

Call your metafield:

Product Siblings

 

Add add this code to your Custom Liquid block:

{%- if product.metafields.custom.product_siblings.value -%}

Also available in...

{%- for alt_product in product.metafields.custom.product_siblings.value -%}

{%- if alt_product.available -%}

<a title="{{ alt_product.title }}" href="{{ alt_product.url }}"><img src="{{ alt_product.featured_image | img_url: '90x90', crop: 'center', format: 'pjpg' }}" alt="{{ alt_product.title }}" /></a>

{%- endif -%}

{%- endfor -%}

{%- endif -%}