Won’t sit in High Chair

Mommas, my 18 almost 19 month old will not sit in her high chair for dinner. She’ll eat breakfast and lunch in it but refuses or has refused to sit in it for dinner the past three/four nights. She wants to either sit in someone’s lap and eat or stand on one of our chairs which we don’t allow since it’s not safe. The high chair she uses is a fisher price booster with a tray that fits in the chair itself. Is this a phase? How do I make dinner more enjoyable? We are expecting a brother in just a week and a half so the laps to sit in will be limited. 🤪 Plus I don’t wanna make this a habit!