Infant formula's is 11.9% import tax on sales above $500 yuan
Bellamy's ecommerce store just needs to ensure they charge less than $500 per sale (including shipping)
Bellamy's HK site charges $440HKD, which is about $367 yuan for 2 x Stage 3 BAL
https://bellamyshk.tmall.hk/
This tax is only talking about imports to main areas of China.. (Not HK)