Not saying this is the best way on that stave, but, for a longbow, what I would do is spend time digging out all the dark soft stuff in the knots with i.e a rat tail file/ bradle/ sharpened nail, whatever etc and thoroughly clean out with rolled up sanding cloth to solid clean wood, then stuff down some tissue to get a rough shape of the recesses on the side and belly and shape some yew wood to plug the holes, fix in with generous super glue(low viscosity even better) and fill any gaps with a soak of super glue. For the back I'd clean out the knot as far as it goes and lay in yew sawdust and superglue and build it up to a bit under the rim of the knot. I'd then chase to a single sapwood growth ring, (maybe leaving a cap of a growthring just around the knot) and work down to dimensions as normal but when putting on the belly profile I'd leave it more flat under the knot (although still rounded) and maybe a couple of mm wider at the knots, proceed to gentle ground tiller, see how it is and proceed... That's just how I would attempt it.
R.D.