Currently, Sibelius does not allow you to create ties between notes in an arpeggiated chord to the full blocked chord, as shown to the left. The Sibelius Reference Guide (excerpt in 2nd attachment) admits this can only be done by manually by resizing the ties. However, when the score is changed, Sibelius does not automatically resize or move the ties magnetically with the score.
Arpeggiated chords are used extensively in piano and harp music, particularly in an Impressionistic style. This is a major setback from Sibelius that requires a lot of manual work from the user to fix. (The best Sibelius can do in shown in the 3rd attachment.) As far as I can tell, no other notation software on the market can do this yet. It would be a major win for Sibelius to be the first one to accomplish this.