[ryderann]

My russets fall apart when I try to mix them up as a salad.

[Spunky]

That is because you are over cooking them.

[Ellendra]

My russets fall apart when I try to mix them up as a salad.

Are you using them the same day they were cooked? If so, try cooking them the day before, and let them chill in the fridge overnight. The chilling changes the starches, making it so they hold their shape better.