To clarify the adding sink to MDA comment.
You should be flying a relatively stable angle and not a dive a drive. So that you do not go below MDA, you have to decide to go-around above MDA. Therefore, you have to add an allowance. Most carriers add 50 feet.
Once you get to this new altitude which is a psudo Decision Altitude, then you call for a decision. At this point, you go-around or not.
Carriers that do not adopt this style of non-precision approach and have an accident may well be open to prosecution for not exhibiting the relevant duty of care.