DevilFish, let's get you on firm ground as an e-smoker. Use the cartridges that came with your device(s). When those are used up, ask again about vegetable glycerine and flavorings.
In the meantime, win over your father to a better way of smoking. While others in Singapore commit slow suicide with regular cigarettes, you are smarter and have found a healthier future for smoking. E-smoking. Talk with your dad. Show him how much you've learned by studying this on the Internet. Make him proud and happy that he's the father of a smart son.
You can do it! Go get 'em.