My son was diagnosed with severe food allergies a couple of years ago. His list was so bad they retested him to make sure they were accurate. They were.  Anyhow, we weren't sure what we were going to give him to drink that would have calcium but I found a GREAT replacement that we all drink. I buy it from Azure Standard at cost which comes to just below the cost of organic cow's milk a gallon, but cheaper than say boxed milk alternatives.  This is the link for the company site VANCE'S DARI FREE But I get mine from Azure

It tastes great and is enriches with Vitamin D. You make it in the blender and you can make it thicker as a creamer.
Enjoy!