Thank you, I knew milk was good for more than putting in cakes and quick breads (instead of water)bath soaks, drinking.
Evidently, the calcium in the milk is in a form that the tomato plants can easily ‘take up’ and use. My relative was in a (very country) store a couple years ago and ran into an old farmer who had beautiful tomatoes. He asked him what he did to avoid blossom end rot (BER) and ‘powdered milk’ was the answer. He’s been using powdered milk ever since (couple of years) & said he has not had a single tomato with BER! At the time he told me this, he was looking at my garden and noticing a tomato here & there with BER. I’ll be trying powdered milk next year - it’s fairly cheap, too!