Advice - thumb sucking baby

My 4 month old is starting to suck her thumb. Any advice? Should I discourage it? I had the worst time trying to get her older sister off a pacifier when she was 2, but I did it. I can't just take away her thumb if she loves it as much as her sister loved her paci. I try to give her a pacifier instead (she's always been hit or miss with it since the beginning), but she still wants her thumb. Any advice? Any good stories that didn't lead to crooked teeth as they got older? What do I do? 😩