Good Morning, @Tershoe.
I can provide you with some insight into your question about merging customer profiles within QuickBooks Point of Sales. After researching to see if merging rewards for customers was an option in our product, I've discovered it isn't. However, I'll send feedback to our Product Developers so they can consider this in one of the upcoming releases. They take feedback very seriously and take the time to review every customer's request. To see what's new within our products, check out our Blog.
If there's anything else I can do to help, just let me know. The Community is always here to have your back. Wishing you continued success.