DEAR AMY: I have a dilemma which is common for my fellow baby boomers. My mother married young and had five children. Mom is now almost 90, the “kids” are senior citizens, and even the grandkids are mostly in their 30s. Nobody wants the “stuff,” like Grandma’s china, that ended up in my garage with Mom’s move to assisted living. I want my garage back! I try talking to Mom about donating the unwanted stuff, but her response is that if I want to get rid of anything I should give it back to her, which is impossible. She is in the early stages of dementia, and can’t really think practically anymor…