I too am looking at this. If anyone is able to shed some light on this next point though it would be great help…
I currently have a UK ATPL, which I obtained having flown a Citation Bravo - C500/550/560 rating, however I haven’t flown this type since 2017.
I currently fly a Citation CJ - C525, as a multi crew operation, however I am aware that this isn’t a multi crew type and doesn’t satisfy CS-25.
What I am wondering is, am I actually able to get an EASA ATPL issued, or does it need to be on a multi crew type? I’m hoping as I already have an ATPL that this won’t be an issue. I’ve asked a couple of the authorities, however I’m still awaiting an answer.