Using fingers 1 2 3 5 (thumb being the first finger)
So opening a Sibelius String Quartet Score writing a simple arrangement, I believe, there should be, a way of assigning 4 notes (C Eb G C) going directly onto each of the 4 staves
I haven't used it myself but I believe the Arrange feature is what you're looking for, Thaarup -it is just a 2-step process rather than the one you are asking for.
As far as I can see, you use either a single staff, or the Grand stave, play the chord in and then use the Arrange feature to 'Explode' the notes onto seperate staves.
Search for 'Arrange' in the Reference manual for details.
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Sib Ultimate Mac
Macbook Pro (2020) 1.4 GHz
OSX 13.3.1
16 GB Memory
1TB Hard Drive
Play the quadad into any one of the quartet parts. Make a passage selection for all 4 parts. Hit [ctrl]c. Hit [shft][ctrl]v. Hit OK. Done. That's Copy, Special Paste, OK.