The Couch was a Castle by RUTH OHI

Two brothers discover that with a little pretending, a couch can be anything.

For Burt and his little brother, spending time on the couch is anything but boring. After all, with a bit of imagination, a couch can go through some remarkable transformations. And so the boys ride the couch like a horse and envision a cowboy pursuit. Later the sofa doubles as a pirate ship battling stormy seas. But when some stage-couch theatrics end in tears, it’s up to Burt to rescue his little brother’s feelings and restore the fun.