I get what the OP means.
She lives in Milan but for whatever reason none of us understand (nor do we need to), these children need to visit X surgeon in a country next to Italy (I'm assuming Switzerland or Austria).
Why the OP lives in Italy when X surgeon is in a different country, only she can explain, but I'm guessing it's something that will take a while. But I do know of other families from country A, based in country B but actually having to be in country C regularly for overly complicated reasons.
It could be that there are legal residence issues, financial reasons, health reasons why living in the same country as surgeon X isn't doable. Let's stop struggling to understand the situation OP describes.
OP, given your last updates I would get the train if that's an option the vertigo-prone child would tolerate. Unless your husband is needed there for moral support, although I assume it's mostly the driving that he'd be doing, if he must be back in between for work. As far as I know, both Italy and the neighbouring countries have very strict mask and Covid pass rules for access to public transport, so I would hope the risk of contracting Covid during your journey is minimal. Can you request to be seated in a quieter car on the train, so you come into contact with as few people as possible?
There are some difficult, almost impossible situations which means families have to uproot themselves and go wherever they need to go so their children have a chance. It's something many people can't fathom, or couldn't even consider if they were in that position themselves. But let's not judge or try to tell the OP that what she's doing makes no sense. It's probably the only option that makes sense for her family.