Thanks for your concern! Yes, quarantine rules apply and they haven't even had their rabies shots yet. If I end up keeping them they would of course come to France with the others, and I have been debating that, even asking someone (if I could find anyone) to foster them just till I leave.
But I have had a long talk this morning with Amanda, John's girlfriend, and I think we have worked something out. While I am away they will live in my bedroom/office, which is very large, and they are used to spending a lot of time there anyway. I will make things as easy as possible by giving her loads of litter bags and litter so that she does not have to scoop, just throw it all out daily. I will get them two new large trays to minimise smell and mess. Actually, the smell is better today since I gave them the second dose of their (vet prescribed) wormer last night. Amanda will not let them downstairs, where they might annoy John or have an accident. My room is parquet, and I will lift the rug before I go, so it will be easy to clean and the landlord, if he finds out, will not have too much complaint. My girls will have to find somewhere else to sleep but that will not be difficult as they can stay in the living room or have another bedroom. They are already used to the smell of the kittens and on the whole are interested but disdainful.
I shall be as nervous as hell, but it is the best I can do.