You might want to tie two together to give each other support,..next year cut one out.
I like to cut back first then graft onto smaller water sprouts the following season. Grafts will
heal together allot faster/nicer and you have a better looking tree in no time.

konrad

Thanks I see what you are saying. Will give it a shot on this plum tree. Thanks again

Konrad

One other question this plum I am going to change over comes out way latter than any of my other plums. Dose this mean when I graft one of my other favorite plums on it will it come out late just like the one I am grafting to. What I am asking will it give me a longer season of my favorite plum?

No, a early ripening plum will still ripen early no matter where you graft it.