Proportional ADR sliders

Is there any smart ways to create sliders with proportional relationship? For example: I have a sample of 1000 ms length and want to shape it with ADR envelope. But if I set an attack value to, say 80% of sample length, then other sliders changes their size proportionally.

Theoretically, I know how to implement this, but it would be a huge piece of code...so, wonder if there are more graceful way to do this.

Thank you in advance!