No don't replace the flax oil - take them both (they serve different functions - both good for her). Flax oil will also help with blood Sugar control (and many other things).
I know a bit about hypoglycemia - it is basically low blood Sugar - i.e. the body is unable to maintain the blood Sugar at the correct level. It dips too low and leaves people feeling shaky and weak. Presumably your friend doesn't have diabetes (otherwise you would have said). If she doesn't have diabetes, do you know which type of hypoglycemia she has? There are 2 types - "reactive" and "fasting".