How do you align an endpoint of a 3D line to a reference point

I have two reference points in 3D space.  Then I connect them with a straight line using 3D sketch.  Simple enough, but when I modify the dimensions of the points the line endpoints do not follow causing me to re-edit the sketch and aligning them again.  I can only align them by dragging, no relations show up to make these permanent.  Any suggestions?

SolidworksSketching