Earlier quoted context omitted.
The device is rated 1TB. Given all of the passwords you gave us we can account for .5TB and we cannot find a free-space map. Ergo there is at least one more password that you're not sharing with us. Seriously, other people aren't dumb.
That's not how partions work for these things. And the people who wrote these security systems thought of exactly this attack vector. If you create a passworded partion, it adds a bunch of extra unused space, that MIGHT be another passworded partion, or might just be random empty space. IE, maybe you have 3 passwords and 200 GB of extra space, or maybe it is actually 4 passwords and 150 GB of extra space that is rand…
"MIGHT be another password-protected partition"
->
"is a password-protected partition"
You can disagree with that thinking all you want, but it won't do you any good if the people thinking that are in control of your destiny.