Add movements rather than just the big three

It'd be good if you could program of say, 4 major movements, rather than assistance weights that are kind of just guessed, as per the situation atm.

Could you give me an example?

Sure, so i'd like to do overhead press as an assistance exercise, I know my max for this is much different to my bench, and want to do it for 5X8 at 60% of its max (5X8 with 60kg). When entering 5X8 shoulder press at 60% into the app, the working weights i'm given are far different from what i mentioned and seem to either not appear or be tied to my bench max. Are you able to remedy that in future?

Press variations are tied to the bench press max. You can override that by not including "press" in the name. Try OHP instead.