if the company won't share the preference stack with you, look up the total amount of capital the company has raised (or ask the question that way - that may be more likely to get an answer). In most cases, the preference stack = total capital raised.
I _think_ you mean most cases preference stack is _at least_ total capital raised... and therein lies the rub... if you have some latecomers coming in at 1.5 or 2x that drastically affects payouts.