DEAR AMY: My two sons are not speaking to one another, after a fight that occurred during Christmas two years ago. The result is that my granddaughters don’t like their uncle and aunt. The three girls are 11, 9, and 6. While sleeping overnight at my house last weekend, I told my granddaughters that I love both of my sons equally. They started to cry. The next day I met with their parents in a coffee shop and apologized. I explained that I didn’t mean to offend anyone and asked for forgiveness. I thought that they had forgiven me until recently when my son said that the oldest daughter (in fift…