Oh, she laughed and laughed... she tricked me!
A light bulb went on.
With 3 kids running around, and especially when we have friends over, it's hard to keep the cups straight. What if each cup had a cozy? Maybe a custom one with a name tag on it? Or just color coded? For now... if we can wrap each kid's cup in their sock, we'll be making some progress.
Someone really should make these (a custom sippy cozy)... For now, I'll reserve the idea for me (patent pending). Cheers!!