If your family is on board with making changes you're in a much better spot already. If the entire family has trouble getting into a better rhythm/finding healthier solutions it might be worth joining Weight Watchers. They're not perfect, but they offer structure and creative solutions that actually taste good. If you're doing this as a family you might even make a habit of taking turns cooking dinner or prepping lunches. Bit of friendly competition?
If you already know how to make healthy food taste good but just have trouble sticking to it, the Fat Nutritionist advises to start small by just adding healthy things to what you'd normally eat. Sugary drinks? Make sure to ALSO drink enough water. Full-fat lasagne? Add a (tasty) salad, some veggie sticks with low fat hummus or whatever veggies you like. It may sound silly but it's easier on the brain than just taking away those things it wants, thus making the transition less scary. Plus your body is getting more nutrients from day one!
Hope that helps a bit.