Alternatively, maybe "Yvm" is a typo for "You've", so "You've made Daphne D52 Dad". But that doesn't make immediate sense. Let me think about Daphne D52. Daphne could be a name or a code name. D52 is a model number, maybe a device or a game. The term "Dad" at the end is intriguing. Putting it all together, maybe it's a puzzle or a cipher requiring substitution or other cryptographic techniques.