I think that's individual countries so easy enough to move around.
Anyway it's a technicality, Mrs Donsdaft and myself only got around to getting Hungarian residency at the tail end of last year.
There's no way they're leaving at the end of March ( or at all really) so don't worry about it.
If I'm wrong* you can always make a dash for Gibraltar
* I was wrong once but we don't talk about it.