Are they in-ground or in pots. Anyway, if it were my rootstocks, I would remove the failed grafted and feed the trees wit fertilizer high in nitrogen to push growth this year. You can try T bud in late summer if the rootstock sized up well (it is hard to bud tiny rootstocks.
There is a good T bud tutorial by Fruitnut in the Reference category.
Also, check this how-to graft peaches. You can skip the majority and go to the last 10 posts starting with the one @ahmad posted. Those are good suggestions.