When our kids were little, we had them share a room but split them up once we realized they kept waking each other up at night. Not in the sweet, playful way, but the crying, bedtime routine all over again way. With a toddler and infant, that was not something we wanted to go through every night. We made the guest room a separate kid’s bedroom. After the kids got older, our girl decided on her own to sleep in her brother’s room for company. His room started out as a guest room, so there was a full-sized bed there in addition to the crib. Over the years they would…