We have on of those Amish Friendship bread starters going, we want to make our own bread. What could be done to convert this starter into a sourdough started, maybe just change the recipe to make the bread???
If you don't mind the first bread being somewhat sweet, you can use it as a leaven. I have. I'm afraid I might not have any practal advice.
If I were in your situation, wanting to do what you are doing, I guess I'd separate it according to the instructions, make one friendship bread, boil some potatoes for a side dish, but really to have the potatoe water.....store the water in a crock and add a portion of the mix (really intended for a friend into the potatoe water (after it cools) then store it in a safe, dark place and give the other 2 starters away.
Its not really practal, unless you know you will continue with it. You can kill your batch real fast if the yeast doesn't get used and more potatoe water isn't re=added in a few days.
You'd have to be in a good routine. But if there's a will, there's a way. You got something cooking in your brain, and there is logic behind it. Go for it.
Now, keep in mind that the bread will have a completely different taste than what you might be used to; but it might not be a taste that you would mind. I can handle it. It will not keep for very long though. Bake and use. In 2 days, it will be even more sour than today. Thats my 2 cent's worth anyway.
I haven't had Friendship Bread in a long time. I think I'll put some goop together and get one started and look for my recipe. We have had a surprise cold spell. I might luck out and be able to bake in a few days......or I'll just do something in a skillet on the stovetop if its too hot.
I think its easier to take sourdough starter and turn it into the sweet starter (like Herman's or the friendship bread) than the other way around. You might be better off to see if someone will just send you some of their dried starter to rehydrate. I use my sourdough for waffles, pancakes and bread, and there are some good looking recipes on the King Arthur site I want to try. As was mentioned, it has to be fed at least weekly if you refrigerate it, to keep it going, and daily if you keep it on the counter. Don't use metal, and don't put a tight lid on it, as it needs to grab yeast from the air. I use a quart mason jar and just use fabric with a ring or rubber band. I just feed mine with flour and water..you can use any kind of flour, rye is supposed to be best, I've never used it. It sure does like the freshly milled WW stuff though! It gets all happy and bubbly.
If you can't find anyone, PM me and I can send you some.