2 Syllables: SU
arching, argent, arming, bargain, barking, barring, broadening, carving, charging, charming, charting, darkening, darling, darting, Darwin, Darwin's, farming, farthing, gardening, guarding, hardening, Harding, harming, jarring, jostling, marching, marking, Martin, Marvin, modeling, offering, parking, parting, sharpening, smarting, snarling, softening, sparkling, starting, startling, starving
3 Syllables: SUU
auditing, blossoming, bothering, discharging, fostering, gossiping, honoring, honouring, marshalling, modelling, profiting, promising, prospering, slaughtering, tottering, vomiting, watering
3 Syllables: USU
alarming, departing, disarming, discarding, disheartening, embarking, enlarging, imparting, regarding, remarking, retarding
4 Syllables: UUSU
Found 70 words across 4 groupings. Skipped 5 excess words of a similar stem.