QUOTE(KenYoung @ Aug 27 2015, 04:33 PM)
BUT i am also insured right? as 2nd driver?
is there any way i can continue use my sister's name on my car im driving (actually belongs to me) to make use of the NCD
BUT
at the side i draft a legal letter to say the car belongs to me? lololollll.... trust within family is not questionable, just being safe by having things black and white

Yes, as a named driver (or not), the car is insured, provided owner gives consent to drive the car.
The difference is no excess on claims for non-named driver.
Insurer doesn't care you pay monthly installment or what, even if you provide proof of monthly payment. Legal wise will follow documentation as stated. Any claims, money/cheque will issue to your sister's name. Total loss will require her signature to sign it off as well.
You may continue to buy a new car under your sister's name and utilise the NCD. However, how far can you go on this ? Forever until death years later ? It's better for you to start from zero and build your NCD history. Everyone need to go through this path. Sooner or later when you buy a more expensive car, you will not regret building your NCD history on a much cheaper 50k-150k car.