She could try using some of the commercial grocery brands and adding . . .
extra butter and good grated parmesan to the bottled sauce when heating.
Someone made a casserole for work with bow-tie pasta, chicken breast and "Cheesy Ragu Classic Alfredo Sauce". I was suprised at how tasty it was.
I bought the same sauce, took it and home added at least 3/4 stick of butter (about 6 tablespoons, maybe more) and some imported Italian Parmesan and dang, wuz it good! The sauce did not break.
Ragu (as mentioned above) has these ingredient: Water, cream, soybean oil, parmesan and Romano Cheeses {Part-skim milk, cheese cultures, salt, enzymes}, modified food starch, enzyme, modified egg yolks, salt, whey(milk), sugar, disodium phosphate, autolyzed yeast extract, xanthan gum, garlic powder, black pepper and natural flavors.
I guess the modified food starch, modified egg yolks and xanthan gum are enough to carry the extra butter and cheese I added without breaking and it did add a really extra oomph of good flavor. I dare say I could have added even more butter and cheese to the sauce and it would have held.