Or search: fickle, erratic, mercury, mercurial, changeful, hydrargyrum
2 Syllables: SU
billiard, builder, filler, filter, Gilbert, Guilford, killer, Milford, Miller, Milner, pillar, Schiller, silver, tiller, Villiers, Wilbur, Willard
3 Syllables: USU
bewilder, familiar
4 Syllables: UUSU
unfamiliar

Found 20 words across 3 groupings. Skipped 10 excess words of a similar stem.