Here is a very tricky situation I found myself in when my wife and I first started managing our finances: My wife couldn't say no. You see when we first married we had made a decision for her to raise the children, and manage the household, while I went out and earned the money. She did a wonderful job at everything, except managing money. She could never tell me no even though she knew that the things I wanted we could not afford. The turning point was on my birthday one year. I had been needing a new radiator for my truck (I'm a car guy). I had found a very nice scratch and dent model at a local radiator shop for far less than one could be had anywhere else. She knew we didn't have the money, but let me buy it anyway. The next week I found out that that purchase had overdrawn our account, and that we were in the negative a little over 200 bucks. At the time that kind of money was hard to come by. I was furious! We had a huge fight, and I took away her responsibility over the finances. She thought the gift would make me happy, but instead it hurt our relationship. It was a turning point, but that radiator will not be forgotten.
The point is say No! However you must, you have to choose your families financial well-being over the whims and wants of those you love. Think of it this way, is giving in to your loved ones every request at the expense of their financial security really loving them? The answer is no, it is not. So don't fall for this trap.
If you find that you are unable to say no, please relinquish your responsibility to someone who can. You will be much better off in the future.