Is there any plugin or script to convert the simple product to variation product and assign it to the parent product. As far as I check each variation product creates as a post, with

1. post_type – product_variation
2. post_parent – Variable product id
3. attribute_pa_ – Post meta with attribute
4. _product_attributes – Attribute in parent product

Can I update this attribute it will be a proper way? or there is any better solution?