Kershaw's Brigade was part of D.R. Jones' Division, Magruder's Command according to the Official Records – Series I, Volume XI, Part II, Chapter XXIII, Pg 3 during the Seven Days Battles. However at Malvern Hill Kershaw and his brigade were shanghaied by R.S. Ewell to support his attack. So I guess you could say they were "attached" to Ewell's Division, of Jackson's Corps, though a bit unwillingly.
I saw an article on Kershaw's Brigade at Malvern Hill written by Daniel Moran. I believe it can be found at:

MilitaryHistoryOnline.com

As to flags, I'll have to leave that one to someone more knowledgable.