Banking, affidavit questions advice

[jasonr3255]

Both UK parents will be retiring in Thailand next week, Married and 75 / 76 respectively Non immigrant o visa obtained already.

Both will have separate Bangkok bank accounts shortly.

In the event that my father should pass away while residing in Thailand what is the most straight forward way they can insure whilst in Thailand, that my Mother would have direct access to his bank account in the event of a death. They do not wish to have a joint bank account, neither do they have a UK will in place.

Advice would be appreciated. 

[macahoom]

 

ATM card?