You are right your MIL is wrong. Stand your ground 💪🏼 they just put their legs anywhere!
Your child your rules. Tell her if she wants to parent a toddler she’ll need to have another 🤣
We have the britax maxway plus as it was the most slimline RF one in my little golf. Show her some crash videos etc! And say FF they can die, RF just broken legs more likely. X
My little one has long let's. But she will be rear facing for a long time. Our car is small. She's fine. We do quite long journeys too. She's never told me she's uncomfortable. Stick to what you know.