2 Syllables: SU
adding, Atkins, babbling, backing, battling, blackening, bragging, chatting, clapping, cracking, crackling, dragging, fattening, flagging, flapping, flattening, grabbing, grappling, hacking, happening, lacking, lagging, lapping, maddening, mapping, matting, nagging, napkin, packing, padding, paddling, patting, racking, rapine, rattling, sacking, sagging, sapling, slapping, snapping, stabbing, straggling, strapping, tacking, tackling, tapping, taxing, tracking, trapping, wagging, waxing, wrapping
3 Syllables: USU
abstracting, adapting, attacking, attracting, collapsing, combating, distracting, enacting, exacting, extracting, reacting, relapsing, relaxing, subtracting, transacting, unflagging
4 Syllables: UUSU
Found 70 words across 3 groupings. Skipped 4 excess words of a similar stem.