Wrong again; there I go expecting Lynn to make sense. Instead, she's got to make Mike look freakishly advanced.
Panel 1: We start off with Mike asking Lizzie if he and Lawrence can play in the sandbox; she says NO!!!
Panel 2: He reminds her that there's room for the three of them; she still says NO!!!!!
Panel 3: He then acts like a kid by saying that they're coming in anyway so she'd better move over.
Panel 4: She responds by CLONKing him on the head with her pail.
Panel 5: Instead of yelling for Elly or retaliating or anything else a real kid would do, Mike muses that girls are territorial like the super-advanced kid he is in the new-ruins.
Summary: If Lawrence starts carrying a security blanket tomorrow, I wouldn't be surprised. I also wouldn't be surprised if we were to see Elly be gobsmacked by something commonplace.