You should provide a more detailed description of how you implement relations of products to the mentioned groups. Is it based on meta fields? Another question - how do you differentiate Customers A, B and C? Definitely, you would end up with an app in the best case. The worst one - is the necessity to build a custom app. Please, let me know if you need any assistance.
If you’re looking a plugin which supports complex discount structures, your best option is our app, Regios Automatic Discounts (4.8 stars, Built for Shopify).
I would strongly recommend creating collections for Discount Groups 1, 2, and 3, but if you’d prefer not to, then you can use the “Specific products” product eligibility option in our app to select the discount groups manually.
Here’s a screenshot of how you could achieve pricing for your family business using our advanced logic builder:
Thank you for reaching out and posting this question!
There isn’t a way to do group pricing natively. However, as suggested by @tobebuilds , you can consider using a third-party app - such as Bold Custom Pricing: Wholesale.
If you have any other questions on this topic, then don’t hesitate to let us know!