There’s lots of things she can have if she’s DF, I suppose it depends on your other child’s allergies too though.
You can make these blueberry pancakes with a milk alternative and you can cook these banana pancakes in veg oil instead of butter. Other good breakfasts are avocado on toast, smooth nut butter on toast, toasted cinnamon & raisin bagels with vitalite, toasted bagel with smooth nut butter, honey and banana, porridge fingers, sausage and beans (just check the sausage doesn’t have milk in and cut lengthways).
For snacks, hummus and raw veg, smooth nut butter spread on apple wedges, violife cream cheese on Scottish oatcakes. Dried figs are a good source of calcium too.
Lunch. There is still lots of things she can have. Sandwiches, check all breads and processed meats, eggy bread, pitta pizza (violife make a cheese for pizza), wraps, soups.
Tea spag bol, roast dinner (Bisto best is DF and you can make Yorkshire’s with alternative milk), fajitas. You can use mayo or oatley cream to cool down spicy food. Lidl’s mayo is DF. Toad in the Hole again can be made with alternative milks but check the sausage is DF. Cottage pie, you can add things like pure or Vitalite to the mash. Spanish Omelette, Jamblaya, Super Veg Pasta.
Hope that’s enough inspiration 