Well this is not directly about mixed marriages and money, but I feel that what gets most couples into financial trouble is a lack of communication, and a lack of understanding of how their money is working or not working for them. The issues most individuals have is spending habits and a lack of doing a budget (most people have no idea where their money goes every month). I feel that both people in a couple need to understand their money and where it is going. Leaving all the responsibility to one person is dangerous and irresponsible. What happens if one person (the money controller) dies unexpectedly (yes it can happen) and then other has no idea what to do about finances or even where the money is, or even if they have control over it (here in Taiwan there is a risk of that).
As for giving money to family members, this is risky, especially to people who have demonstrated that they are poor with money, if I was married I would never just give money to my in-laws, giving money to people with money problems almost never solves their money problems. They need to change their habits first, if you just give them money they will waste it. I would want to know that they are going to handle the money "responsibly". After all as a few other posters have said, it is important that you take care of you and your spouse first, then when you are in a strong position to give that is when you give. I know people will say but what about traditions and obligations. Traditions are great if they are handled in a responsible manner, I am not Taiwanese so if I eventually marry my girlfriend we will not live our lives 100% Taiwanese, if she demands this well I will not get married as it is probably not going to work
A lot of what people have said in this thread I feel, could have been solved with better pre-marriage communication and post-marriage continuation of that communication

. Be married is not always easy but when you can't discuss money in reasonable ways well things will get tough. And financial trouble is the number 1 reason for divorce in N. America.
So in short everyone should understand their money and how it works (or doesn’t).