7 cans of lemonade concentrate
Sugar to an SG of
water to 3 gallons
3 tsp yeast nutrient
3 tsp yeast energizer
3 crushed Campden tablets or 1/2 tsp K-meta
This time around I used Lalvin 72B-1122 yeast. Results are similar as using Montrachet.
I started my yeast starter in a 1/2 gallon jug. I only used half of the 1/2 gallon jug so that I get lots of air. I put an airlock on it (because I have a yet again a fruit-fly problem this year). That way you can add your lemonade must bit by bit until the 1/2 gallon jug is pretty full. Once you get your yeast starter going, you should get all your other supplies together. Maybe wait a day or 2 to let the starter take hold.
Let the lemonade defrost, add some water (I didn't boil it this time - I just hoped that the campden tabs would do their thing), and other ingredients.
Stir really well. Make sure you get all the sugar dissolved. Keep this in a very cool place for a while. When the starter has a good layer of foam on top (if unsure, wait a day, and then it will be fine), add about a cup of your lemonade-must. If you do this in the morning, let's say, then check on it at night again. If it's still fermenting, add another cup. Keep doing this until the 1/2 gallon jug is almost full (but that you've left about 2 inches of space at the top).
When it is almost full, you can start adding your starter to your hard lemonade. It should take off.
If that way doesn't appeal to you, I would do only one thing differently: Don't add all 7 cans of lemonade at the same time. Do everything the same, except add only 3 cans of lemonade. When you pour your starter in the must, let it sit a day and see if fermentation takes off. If it does, add the other cans - can by can (similar method as the starter method) - one in the morning, the other in the evening. Those yeasties are so stupid, they won't know what hit them.
The question about sweetening vs. non-sweetening at the end of fermentation. You'd treat it as if it were any other wine. I would make sure it sits at SG 0.990 for about a week (at least) before you stabilize it with sorbate. Then let it sit for a few days, and stir the beegeesus out of it, so you don't have a lot of mess to clean up due to popping corks. Sweetening is up to you about how much. I'm an old sourpuss, so I didn't add sugar at all. It was like eating a lemon!!! SOOOOO good! So, sweetening is matter of personal taste.