allets, maybe you can give her fresh or chilled EBM to try? or you can scald the milk before freezing. I read the following from the LLL website:
The key is to scald freshly expressed milk before storing it, to deactivate the lipase enzymes while leaving many, if not all, of the nutrients and immune factors intact.
To scald the milk, put it in a glass or BPA-free plastic container and heat the container in water. You can use a pan on the stove, a crock pot, or -- the method that many mothers find easiest -- a bottle warmer. Just make sure it's not the type that turns off automatically when it gets too hot.
Measuring with a digital cooking thermometer, heat the milk to:
144.5F/62.5C for 1 minute or
163F/72C for 15 seconds or
180F/80C and immediately remove from heat
Place the container of scalded milk directly into a bowl of water and ice (glass may crack; use a plastic container for cooling). The ice bath cools the milk quickly and prevents bacteria growth. Once the milk is cool, store it as usual. Try a few test batches before you start to build a stash.
Microwaves aren't recommended for scalding because they heat unevenly and you can't tell when the milk is at the right temperature.