Put the grapes on a perforated grill sheet or in a grill basket and grill over high heat, tossing occasionally, until they just start to burst and have grill marks. Be very careful not to burn the grapes or yourself. Transfer the grapes to a plate to cool completely.
Meanwhile, grill the peach wedges over high heat, turning once, until lightly charred and grill marks are visible. Again, be very careful not to burn the peaches or yourself. Transfer to a plate to cool completely.
In a large pitcher, combine RinQuinQuin and rose with simple syrup, then add brandy and grilled fruit and stir well. Top with club soda, if desired. Refrigerate until sangria is chilled and the flavors are blended, at least 1 hour and up to 8 hours. Serve sangria over ice.