Hello Insanity394 and welcome to 40konline.
I am not sure I understand your question. The Deathwatch are a collection of Veteran Space Marines that are drawn from any of the existing Space Marine Chapters to serve the Inquisition for a set period of time. As such they do not have a dominant gene-seed from which to make a successor Chapter.
Simply put the Deathwatch do not have a founding Chapter so can't have a successor Chapter.
Can I ask why you asked the question? What is it that you are thinking of doing?