a sealed multilateral junction system provides fluid isolation between intersecting wellbores in a subterranean well . in a described embodiment , a method of forming a wellbore junction includes the steps of sealing a tubular string in a branch wellbore to a tubular structure in a parent wellbore . the tubular string may be secured to the tubular structure utilizing a flange which is larger in size than a window formed in the tubular structure . the flange may be sealed to the tubular structure about the window by a metal to metal seal or by adhering the flange to the tubular structure .