Yes, calcium is good for them but it should be included In The foods that they eat. Candy has done the math on portioning calcium to "sprinkle" I don't remember it off hand so hopefully she will come back me up here. It is VERY easy to overdose on supplements by just adding them willy nilly.
Think about this; a month's worth batch of BML contains 2 teaspoons of calcium, and it is one of the highest calcium diets available. When you sprinkle calcium on food, are you sprinkling exactly 1/15th of a teaspoon? If you are feeding a recognized diet, there is NO need to do this. If you are not, please resource diets and find one which works best for you so that your glider can receive balanced nutrition.
I also know this will not be a popular statement, but unless your vet is a glider SPECIALIST, most vets know much less than we do about diet. Until a few years ago, many of them recommended cat food for protein. It has also been shown recently that HLP is much more commonly caused by infection of various kinds that leaches calcium from the system and is almost never due to diet other than extreme cases of malnutrition.