Hi @MichelleK and both congratulations for finally being able to travel to Australia to see your new grand daughter - I can’t imagine the relief at being able to arrange your family reunion - but also to sympathize with your worries over tests.
We’ve just returned to the UK from France for a sit (we have residency so can move freely across borders even if compelling reason needed any time which helps) but even on arrival yesterday, we had an anxious wait after the handover while we waited for our h/o test results from the airport. All good as I think reassuringly they are in most cases 
With the continual easing of restrictions we are seeing at the moment, this will get easier over the coming months I’m sure 
Looking for somebody who is already in Spain will make one part of your puzzle easier, and I’m sure you’ll find someone to help. We do ask that only last minute sits are posted in the forum, so I have removed your dates so that this is a more general post But one thing you can do is to embed the link to your listing in your forum profile - you’ll find the instructions here:
How to add a listing or profile link to your FORUM profile
This will enable members in the forum to find you.
My only other advice would be to check over your listing to make sure it has as much information as possible for people viewing it and perhaps add a few internal photos, just so that applicants can see where they will be living, cooking, sleeping etc. Having lived in Spain I know that the outside space is just as, if not more important (especially during the warm/hot months), but it’s an often mentioned point here on the forum that people do like to see the inside too
We’ll all be excited to see a reunion picture in April, but if there’s anything else we can help with inbetween, don’t hesitate to ask.
All the best
Vanessa and the forum team