In my opinion, the filthiest four-letter word in the English language is, Diet. Besides the fact that it usually leads you to saying every other filthy four-letter word in the English language, it fills people with short-lived hope and motivation, then leaves them on their ass, crushed and unhealthy.
However. switching Greek Yogurt for sour cream has still yet to be detected. It's so good, I may never buy sour cream again. I love using avocado in my sandwiches and on toast in the morning, instead of Mayonnaise or butter. Vanilla almond milk is awesome in my coffee, and the Kid loves it, too!
If you're trying to find a way to move your family to healthier eating habits and cut back on fats and sugars, try food swaps. Work to completely revamp your shopping list, with the goal of being in a different, much healthier place in a year.