If you plan on leaving the back of your bow like the way it is in the pics, I would reconsider. I have made a few osage bows and after one good lesson on one, will never leave those islands of grain around knots again. Here is why. When drawn bect those islands of grain around the knots pick up extra tension and can ( and have ) delaminate. When this happens they often take the wood under them with them and you have a broken bow.
This happened to me, I asked experienced folks why and that is the answer I got. Most had had the same happen to them. Best to have a clean single growth ring on the back with none of those islands around knots. I would hate to see such a gift to a child fail. If nothing else, at least ask around a bit before you commit to leaving the back as it is.