If A(-1,3,4), B(4,6,3), C(-2,1,1) and D are the verticies of a parallelogram, find all the possible coordinates for the point D.

So I let D be (x,y,z), then I worked out vectors AB,AC,AD,BC,BD,CD and after this I don't know what to do. (am i even doing it right?) Can someone help me with this question?