Mike,
I did assume you were trying to graduate a velocity curve, so the advice i gave was for that.
To go from Piano to Forte is even easier. Remembering that markings are ignored in LIVE PLAYBACK, you'll see above each note a blue bar (for the blue voices, green bar for the green etc.) representing velocity. Here's a example of my procedure (one of them).
I don't know how competent a keyboardist you are, so i'll assume on the side of competent.
Turn on Live Playback (The button with the lightning symbol). Record your phrase. Above each note will appear a blue vertical bar. This represents velocity. The whole bar (pale grey) is quite naturally 100%. The blue section represents the velocity of the note you have recorded. (hit it hard and it will be almost all blue, hit it soft, and there will be more grey. Easy)
At any time (while stopped) you can simply click on the bar in any place, and the note will be set to the new velocity.
Now, i said that markings were ignored in Live Playback, and that remains true. But if you record without live playback, you can still activate it.
So, you've entered your phrase, and now you wish to adjust the velocity. You've heard that your one sample HASN'T changed dynamic, despite the markings. Don't panic.
Turn on live playback (the button with the lightning symbol) Highlight your chosen phrase (Blue Box) and go to Transform Live Playback in the dropdown Play menu.
It will ask you if you wish to 'set a velocity' for each note. Use the default (I think it's 64) or set your own, then press ok. Above your phrase appears a vertical velocity box for each note, and you are at part one again.
If you wish to revert to non Live playback after, ensure you save!
This is a quick workaround develped from the frustration of using the Cres/Dim plugin, IMHO the worst part of Sibelius. (Should be integrated)
It's easy to do, and you have an advantage with VSL samples, as i'm coping with Miroslav on my little laptop while studying here.
Note, it's worth going to the thread i started in Composition, and see if the setup is useable. I don't know how you've got Sibelius wired into a sequencer, so if you turn off Live playback and your sample returns to a single velocity level, then turn live playback on on again, (and of course you saved it earlier), and record into sequencer making any neccessary audio adjustments. If you then wish to 'tidy up' the score for printing, you've got your audio recorded, and after turning off Live playback ,and any engraving adjustments, you've also got a printable score. Winner both ways.
Also note i use two scores. first the working score (playback adjustments), then adjustments to end with a printable score. I used to do it the other way round, and it took a lot longer.
Regards,
Alex.
I haven't tried to record in Sibelius with the audio track feature, so i don't know if it will work. Perhaps something to try in the future.