Or search: loyal, fealty, disloyal, fidelity, trueness, allegiance, commitment, dedication, enlistment, patriotism, cooperation, nationalism, communalism, regionalism, staunchness
2 Syllables: SU
jointly, loyally, loyalties, noisy, oily, royally, royalties, royalty
3 Syllables: SUU
joyfully, noisily
3 Syllables: USU
adroitly, conjointly, disloyalty, employee
3 Syllables: UUS
appointees

Found 15 words across 4 groupings. Skipped 1 excess word of a similar stem.