Here is how Dorico slurs grace notes in this particular situation:
To my taste however, it should look something like this (tweaked in Engraving mode):
Is there a way to get this done by default?
Not yet, but it’s been requested already on this forum so the Team knows, and it is probably already on the pile of the To-Do stuff… Slurs and grace notes are seldom spot on, they always need some massage. Or you mess up with the other cases, which is not a good idea!
Thank you for the reassurance, Marc