intervene, slide in, interpenetrate, permeate. put between, introduce, import, throw in, wedge in, edge in, jam in, worm in, foist in, run in, plow in, work in
interpose, interject, intercalate, interpolate, interline, interleave, intersperse, interweave, interlard, interdigitate, sandwich in, fit in, squeeze in
let in, dovetail, splice, mortise
insinuate, smuggle
infiltrate, ingrain. interfere, put in an oar, thrust one's nose in