Is JaeHwan(Jay) Min related to Grace Min and Austin Di Giulio to Joe Di Giulio?
Probably not and very likely (in that order)
The two Di Giulios are both from Newport Beach California so it's not a far cry to guess they're brothers.
Edit: and there's this http://articles.dailypilot.com/2010-...-junior-tennis
But Jay Min is from Cali, while Grace was from Georgia. And Min seems like a pretty common last name so i doubt it.