gcommerce-8.x-1.0-beta5/modules/gcommerce_store/gcommerce_store.links.action.yml

group_relationship.group_store_add_page:
  route_name: 'entity.group_relationship.group_store_add_page'
  title: 'Add existing store'
  appears_on:
    - 'view.group_stores.page_1'

group_relationship.group_store_create_page:
  route_name: 'entity.group_relationship.group_store_create_page'
  title: 'Add new store'
  appears_on:
    - 'view.group_stores.page_1'