Directs are only personally liable for the debts of a company in...

Directs are only personally liable for the debts of a company in the following situations:

https://asic.gov.au/for-business/your-business/tools-and-resources-for-business-names-and-companies/asic-guide-for-small-business-directors/directors-liabilities-when-things-go-wrong/

Unless they've breached one of those rules, only then will they become personally liable for the company's debts. Remember, each company is it's own separate legal entity and the failing of one company cannot be transferred to that of a separate company (again unless one of the above have been breached).

This leads to the following questions that would need answers for:
1) Have one of the critical key areas mentioned in the link been breached (and remember this is only for debts incurred WHILE insolvent)
2) Can a director of one company that has gone into liquidation still be the director of another company - I haven't got a definitive answer on this but it appears from a cursory check that they can.