Complex sentence: Building on the idea, the aspiring artist's father had made "Maison Dewachter" (House of Dewachter) one of the most recognized names in Belgium and France and he was embarrassed that his offspring would waste his time with something as useless as painting.
Split into simpler sentences: Building on the idea, the aspiring artist's father had made "Maison Dewachter" (House of Dewachter) one of the most recognized names in Belgium and France. As such, he was embarrassed that his offspring would waste his time with something as useless as painting.