It's hard to give specific advice when we don't know about their views, but what I will say is to try and understand their perspective and proactively try to understand what issues/questions they may have and prepare answers as best you can to them to try reason with them.

The other aspect is understanding formality. A lot of asian cultures have strict cultural formalities to matters like this, so it's best to make sure you understand how to handle the matter from this perspective.

Ultimately, I think it's important to just be honest and up front. From personal experience, many people will initially appear very difficult to get approval from, but ultimately if you can get to the very heart of the matter, that you're looking out for their daughter's wellbeing and happiness, many will come around to this.