Sunny is Li'l D's father.
Let's think about it now. Child Sunny was rather short. Li'l D is rather short. Child Sunny also had a similar face shape to Li'l D's. Sunny is musically gifted, and Li'l D's official profile on the (now-down) website said that he could play many instruments. Plus, there's gotta be a reason why Li'l D admires Sunny so much, besides the music...
Phil is actually from the future.
Let's see. He seems to consider himself normal, like everyone else is a techno-head. Building gadgets out of thin air is normal. He appears to be in unusually good shape (see "Big Robot on Campus") for a geek.
Both of his parents share eccentric looks and likely behaviour with him.