Hi Kris! What a lovely idea. For many bakers, using 1 cup of starter in a recipe (227 grams) is a good starting point. You will want to remove 113 grams of water and 113 grams of flour from the recipe to compensate for the water and flour that is contained in your starter. As for reducing the yeast? You can since you are using a fed starter. Perhaps cutting back by 1 teaspoon. Your rise times may be a bit longer since sourdoughs are notoriously slow risers, but with that small amount of instant yeast, you will still get a wonderful lift. Happy Baking!

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