Or search: irs, fisc, uscb, funds, trough, fincen, deposit, bursary, finances, depository, repository, subtreasury
2 Syllables: SU
every, feathery
3 Syllables: SUU
Beverly, charities, Chesterfield, cleverly, destinies, elegies, enemies, enemy's, evergreen, Genevieve, heresies, jealousies, leathery, legacies, lethargy, melodies, memories, parodies, pedigrees, Pericles, recipes, remedies, reverie, treachery, treasury, verities, westerly, yesterday, yesterday's
4 Syllables: USUU
accessories, accessory, amenities, barbarities, disparities, extremities
5 Syllables: UUSUU
similarities
6 Syllables: UUUSUU
irregularities, peculiarities

Found 40 words across 5 groupings. Skipped 2 excess words of a similar stem.