A lot of companies sell base products that can be customized with the purchasing companies' individual fragrances. How does that work with testing? I was under the impression that PET testing would not be required because the product being sold should have already met those requirements. But what about stability testing? I would think with the variety of fragrances that the base product could have added to it that stability testing would be necessary, but I'm not sure and would love any input from those with more experience. Thank you!