Yep you are right Williamr he is very similar in age. However here in Australia there is a legacy system whereby if he dies first his executor becomes mum's . Though the executor can decline and the court can appoint another executor who is usually the main beneficiary.
For mum assets wise there is likely to only be her nursing home bond to be returned after she passes. Most other assets will have been sorted as per mum's wishes earlier on.
Hi MrsTerryN
I must say it sounds a crazy system to me.
I know of a case where the siblings of the father thought they were entitled to the father's estate because the son was reasonably well off.
The father did not want his brother's / sisters to be involved in the winding up of the estate and appointed his son as the executor.
The siblings did not come to the funeral.
William