100 Wishes to Steal My Life

My family can see a countdown above my adopted sister Melody. They think she'll vanish in 100 days, so they grant her 100 wishes. She takes my dress, my gun, my wedding, even my husband and son. But they don't know I'm from another world too. When the countdown hits zero, I'm the one who vanishes. They later learn the truth and fall into regret, but I've returned to my own world and never look back.