Although visits to Trish and the family are not recommended at the moment, unless of course you have a close relationship with them, written condolences are appropriate.
My understanding is that the four children’s names are Melissa, Ainslie, James and Simon. If I’ve got that wrong, please let me and everyone know immediately! (It might be worthwhile holding off for a day or so just in case).
The address is 11 Vasey Crescent, Campbell, ACT, 2612.