2hrs is definitely within the window MH (and other carriers) won’t allow free refunds. Read your insurance T&Cs too, see if it will cover this situation as there is usually an allowed window for delays.

If it works instead, you can ask if MH is willing to rebook all of you on MH 1459...

Of course, it also depends on the flight dates: the coronavirus situation is making things very difficult to assess. e.g. MH is now offering free changes, with the nationwide lockdown... perhaps MH’s approach to cancellation too will change in the future.