Or search: narration, tearjerker, communicatory
1 Syllable: S
Rep
2 Syllables: SU
average, beverage, fastenings, happenings, hemorrhage, leverage
3 Syllables: SUU
crevices, decorative, equipage, gatherings, labyrinth, mattresses, menaces, narrative, Nazareth, necklaces, negative, palaces, pasturage, patronage, prefaces, relative, sedative, terraces, therapist, threatenings, vassalage
4 Syllables: USUU
collaborative, comparative, competitive, correlative, imperative
5 Syllables: UUSUU
representative

Found 34 words across 5 groupings. Skipped 6 excess words of a similar stem.