Or search: rep, flak, flack, bagman, sample, apology, treater, roadman, alderman, delegate, specimen, symbolic, precedent, proponent, spokesman
1 Syllable: S
Rep
2 Syllables: SU
beverage, hemorrhage, leverage
3 Syllables: SUU
crevices, decorative, equipage, menaces, narrative, necklaces, negative, prefaces, relative, renderings, sedative, sensitive, sentences, tentative, terraces, threatenings
4 Syllables: USUU
apprentices, commemorative, competitive, contemplative, correlative, imperative, insensitive, remembrances
5 Syllables: UUSUU
argumentative, representatives

Found 30 words across 5 groupings. Skipped 5 excess words of a similar stem.