Rules for Changing flights

[WeeGraeme]

I bought tickets to fly from Brisbane to Amsterdam (QF tickets on EK). I then had separate flights booked from AMS to ABZ which was actually my end destination. (I had something planned for a few days in The Netherlands). I'll almost certainly have to change my plans, due to a medical issue with one of the travelling party. I will no longer specifically need to travel to The Netherlands. Is there an option to change destinations? Or would that require cancelling the flights and getting a credit which would probably be more restrictive? Even though my change isn't covid related, it appears that I'll be able to change my flights to Amsterdam under the covid rules, which will mean only a fare difference and no change / cancellation fee.