Watch the Mixing the Chord Forms online guitar lesson by Joe Dalton from Fretboard Epiphanies
Very often we want to change from a D to an A or a B to an E or other chords in other keys that are four apart and we want the melody notes close together. Instead of jumping up or down to a chord with the same form, it is good to find a chord close by. This would of course be a different form. I think these next examples will get you started.