(Strip Number 7133, Original Publication Date, 20 February 1983)
Panel 1: We start things off with Mike trying to color something only to have Lizzie roll a toy car all over it just to be an irritant. Mike tells her to keep her stuff on her side.
Panel 2: Her response is to tell him that this isn't his table.
Panel 3: The strip most people will tape on the fridge starts with Mike whining to Elly about how Lizzie keeps putting her stuff on his side of the table.
Panel 4: Elly tells them that the masking tape she's holding should solve the problem.
Panel 5: Her solution is to mark the boundaries so that no one can pull the stunt Lizzie did.
Panel 6: Since the real problem is that they're being forced to share a living space that isn't big enough for the two of them, it should come as no surprise that they abandon the coffee table to sit on the couch. It should also come as no surprise that Mike yells for MAH!!! because Lizzie's taking more room than him on the couch.
Panel 7: Nor is it a shock that Lizzie tell MA!!! that him gots alla window.
Panel 8: A few hours later, Elly tells a goggle-eyed John not to ask why the couch, coffee table, picture window, Farley and her shirt have masking-tape dividing lines on them.
Summary: The answer is that they're bored children with no real sense of personal space forced into each others presence when they'd rather not be. That being said, the Lynnsight will probably simper about Aaron and Katie not getting along unless it's about how Alan was an interloper who was handed everything on a silver tray because he has a willy.