think of your money offshore for gambling as your money. Not money that you share with the family. If you loose it all then your family didn't loose out on anything.
If you start to get more money offshore than you feel comfortable with keeping all to yourself, then ask for a withdrawal and realocate those assets to something a little more ligit.
Now if something were to happen to you. Leave with your attorney a letter sealed and addressed to the executer (sp) of your estate. The letter should contain information on all your offshore accounts, usernames and passwords, along with instructions on how to request a check withdrawal for all funds (in your name).
Once they get the checks they can be deposited into your checking account and they become part of your estate.
This way the books have no idea you have passed away, and your heirs will be looked after.
good luck