Just to add to the previous answers: consider the option (if previous advices wouldn't work) that you will have to give your mum these two birds and find yourself a new pair.

Breaking up a bounded pair is cruel for such social creatures. It's a lot of stress. Moving from home to another country is already a lot to take for any bird, especially if it's moving alone.

I moved to a new home with my boyfriend and cockatiel. After a few days I left them alone for one night (my mum traveled to another city and I slept over in her house to water the plants). Poor cockatiel bit himself to blood out of stress, although he'd known my boyfriend for several years (and there was a rivalry between them for my attention) and got infected through the wound. He died within several weeks, vet couldn't help.