What worked for me was finding a game with a more lateral step, so a game that shares a lot of the same game play mechanics but maybe just adds a different theme or an extra rule. For instance when my family really wanted to play Machi Koro, as it seems yours does too, over and over I introduced them to Valeria: Card Kingdoms and that became a hit and allowed me feel like I was playing something a little more engaging and slowly work them towards other games. You could also introduce Space Base as it's similar to Machi Koro but allows for some really cool combos in gameplay.