@Martin *******
, sorry about that. Then you need to plan to leave the country once her covid extension is up (means governments consider it's the time of that traveling is no longer impossible).
Now here is a bit off-topic.
Before you decide to let her overstay, you better check with her school if there is any problem with her being on overstay (=technically illegal immigrant) for her to be a student with that school... or consider if it's okay to keep 'secret' for school activities..