Hadar has been kedem for quite some time already. Until last year kedem had a monopoly on retail kosher grape juice. All brands are either owned by them (IE: Hadar) , copacked by them or they sold concentrate ( IE: natures own). Last year Welch's/Manishewitz began their own line and this year Natures own began purchasing concentrate from someone else.
But no chance that the FTC gets involved from an antitrust perspective, as the kosher market is just a small segment. There a plenty of wine companies out there, etc. etc. etc. The fact that the Herzog clan controls the kosher wine market (and through other subsidiaries such as Medek, etc. try to control other markets) probably doesn't reach the FTC antitrust radar screen.
I recall when Kedem first branched off into Haddar's territory (IIRC it was the Geffen brand that they started with). The owner of Haddar at the time got so upset, he tried to go into the wine business in retaliation (and IIRC he claimed that only his mevushal wine is mevushal according to all shittos, while Kedem wines are mevushal by pasteurization which some opinions don't accept). Well, we all know how that ended. I doubt anyone even remembers what brand name he used (I don't).