What happens when a chemist tries to cook.
Sodium citrate is pretty easy to find online and can go in all kinds of cheese sauces. You can even use it to make a stovetop mac and cheese with your favorite cheeses that won't get goopy or oily. The other chemical Nile used isn't really needed, it's probably more so it holds together into the sheet shape for mimicking singles.
Another alternative to getting sodium citrate is to add American cheese to your cheese blends. Not singles, but deli counter/block cheese. It's enough to smooth out sauces made from other cheeses.