Any constructive advice would be most welcome
First things first: make sure that your own assets are secured. Blood is thicker than water, and you wouldn't be the first one to have his assets stolen for the benefit of the family. Your wife and the family will be expected to help in any way, particularly if they have assets that can be used to help the brother. So, no matter how much you trust your wife - move any spare cash into an account that she has no access to, and make sure to check the title deeds online of any property that you own in case a loan gets secured against the property.
Secondly, bankruptcy is only available if the circumstances were beyond their control. So, the court will take a close look at the operations of their company before deciding if bankruptcy can be offered.
Thirdly, if bankruptcy is offered, then the conditions are strict. The court will analyse their assets and decide which will be sold, which normally includes property. They then have to submit monthly accounts to the court, showing their precise financial situation. The court will decide on a repayment plan for these debts, taking into account their income and expenses. They can expect to live a very basic lifestyle for the period of repayment, including only being allowed to rent a very small property and to only have a car for commuting purposes only.