"It says, "You can mix Bellhammer 7 with Bellhammer Light. but can I put all of them in one bottle at a time?

Depending on the engine oil capacity of the car, Bellhammer Light has a liquid capacity of 260ml, Bellhammer Seven has a liquid capacity of 330ml, and the recommended amount to add is 5-10% of the oil capacity.
The recommended dosage is 5-10% of the oil volume. There is no problem if you add the entire amount, but due to the nature of the oil, the dosage reaches its maximum at about 15% of the oil volume, and it is difficult to see any significant improvement by adding more than that.
It is not necessary to use all of the product, but you can store the remainder, and use it at the next oil change.