In very standard string writing, a trill will often times have a little pair (or more) of grace notes at the end, a turn, to show the way the trill should end and then lead into the subsequent material.
likewise, multi-stops are often written as a grace note (or pair of grace notes) that are tied into the “real” note (or slurred, depending how many strings are involved in the multi-stop).
And of course, there are very often situations in solo string writing where BOTH are required: a trill ends a bar, has a turn at the end, and the next bar starts with a multi-stopped chord.
This means two different types of grace notes.
It is obligatory that Dorico eventually include a means of achieving this result without resorting to work-arounds.
