DEAR ABBY: My stepdaughter has an 11-year-old daughter I’ll call “Kristina.” Kristina is very well-behaved, but she’s being taught at home that love is measured in dollars. She is constantly hinting about gifts and candy she wants. It has gotten so bad that when I keep her, I postpone errands because she invariably finds something in every store that she needs or wants. I don’t mind buying her things from time to time, but the items I purchase are sometimes returned to the store or sold by her mother. Although Kristina is an only child, she is not my only grandchild. If I buy a gift for anothe…