That tends to catch people off guard when I tell them that Charlie Brown was originally Lucy's babysitter! Then, he babysat Linus. Heck, the VanPelt clan popped out a lot of kids to be babysat by Chuck. Of course, they grew up a Little, hitting that bizarre ceiling of whatever age the kids are supposed to be. (Except Rerun who only advanced as far as Kindergarten.)But the cast of "Peanuts" aged a few years over the course of 49.
I've aged my characters about 2 years total throughout the strip, moving them into Middle School (Or Jr. High, as I called it.) and it's been fun, although I rarely even SHOW them in School, so it was largely just an excuse to change the human designs a bit.
I AM curious if D.C. really is intending this changeover, or if we're reading too much into it. I mean, how many episodes of the Simpsons make references to the kids advancing a grade or having a Birthday without ever altering the basic status quo?