I don’t know about legality. You asked if it is fair, I don’t think it is fair that he can somehow end up with a chunk of inheritance from a person he most likely never tended to or spent significant amount of time with.
For your workmate it is a lottery but for his wife it is almost her father’s memories.
Unless his name is in his father in law’s will, then he won’t be entitled to anything. If the will leaves inheritance to his daughter and son in law then that’s a different story. Doubt it would be worded like that though.
@Trion is right - she definitely has a right to their family home. On the other hand, her dad’s money isn’t his to be shared. Legally it won’t be the same.
I don’t know Australian inheritance law but I’m pretty sure that if that money from the dad isn’t in a trust for her and her sister and she takes receipt of it while she’s still married to him he can make a claim to half of her half.
If she just gets a lump sum while he’s married to her he has a claim, will or not I think.
Definitely worth looking into for him if things get nasty.
I think I remember reading that my ex wife would have been entitled to part of an inheritance I received from my great uncle when he passed away and it made me shake.
Everything you acquire during the marriage is split between the two, that’s how I know it. That’s why it’s best to get rich and buy everything you own before getting married