Pics would really help.
Are you going for bendy handle?
I wouldn't say you need sinew for juniper but I know ERC is a juniper and it is well matched with sinew.
Generally, I would try to put the knot in a non bending handle if possible and then try to keep it from the edges if not in handle.
I did a sinew bow ERC with lots of knots and I decrowned it, reamed out any punky spots on back and put some short sinew strands spidering out from wood glue and sawdust and then let it dry. The sinew sticking out was not glued at that time. I layed it down later with hide glue onto the back, let it gel up, and then and went over it with the rest of the sinew job. Not sure if that process really helped but the bow did just fine.
My first bow was a ERC sapling with a significant crown and backed with 2 layers thrift store silk skirt. It was filled with knots, too short, took massive set, but still survives and pulls around #60. It is scarey.
Once you have pics you'll probably get a lot of other folks opinions too.