You can ask for whatever, but you have to consider the strengths and needs of your counterparty. Boston would much, much rather parlay DeBrusk's value into an LD answer because he is owed a raise. There's nothing forcing them to target OEL either, as this year has a pretty solid number of D in FA and available in trade that don't cost as much.
I think if you agree to DeBrusk, Moore ($$), Ritchie ($$), you can ask for two nice sweeteners because you're going right down the plate for what Boston wants to do. That has value to them.
In a vacuum, yeah you should be able to get Studnicka in an OEL deal. But if you consider market factors and team needs/wants, it's not a realistic ask, nor is it the ask that gets you the most value from Boston.