Saramc ,after my must gets done how many packs of turbo yeast and sugar should I add ?
Ok, quick calculation of your OG based off of 10# sugar alone, not counting the five cans concentrate, has you at around 1.094, which if your bread yeast utilizes all of that you would reach an ACV of around 12.4%. In all reality, the grape flavor is going to be quite low since the typical recipe uses 2-4 cans per gallon, while you would use four cans per gallon to get 1 gallon of drinking unfermented juice with a typical SG of 1.060...so one can per gallon in your must would likely raise the SG by 0.015. For this case, let's say your OG is roughly 1.109, which gives a new ACV of 14.46 IF the bread yeast ferments it all out.
If you are going to use turbo yeast, which I would not on this, you need to add enough sugar to have a new OG of at least 1.165 to reach 22% if the turbo yeast will take over the bread yeast, and I would add it sooner than later because it is difficult to establish a yeast in an established alcohol base, such as waiting for this to ferment out and then pitching new yeast.
--FYI, takes five cups of sugar to raise SG of five gallons by 0.020--you need to raise SG by 0.056 to get there, 1.165ish. Based on my calculations you could add another three cans per gallon of grape concentrate, that would account for 0.045, but 4/gal would take you just over the target. Plus, you would really need to add it in stages, like every drop of 0.030 points, need hydrometer, because a yeast cannot handle all that fermentable up front.
*BUT, and I seriously mean it, you would be better off just letting this experiment ferment out and punch up the ACV with some pure grain or vodka if that is what you want.
Recommendation, if you want this sweeter than where it ends up finishing be sure to stabilize with k-meta plus sorbate after it clears and sweeten to taste with sugar or perhaps some frozen but thawed concentrate to bring some of the concord back. Plus, invest in a hydrometer, please.