hi .I had the same problem. you take very hard way. the easy way convert your object to sub-D and than there work on edges with patial crease edges/
convert the object to sub-d
select the edge that you want(hard edge)
in the menu sub-d click on prtial crease edge 1 or 2(more harder)
or full crease (that is very hard edge like table or knife edge)

just try it is very easy and simple if you not happy with edge you can uncrease edge in the menu(undo)

after you finished you can convert the sub-d to oplygon again. but when you convert the sub-d to poly you have to be carreful.need some changing in the option tesselation method: vertice and the level should be 1 or 2 that is the best way return to poly. but sub-d has great view in render. good luck