Hi Steve, et al
Joe's suggestion did the trick (thank you sir). Getting to the dialog box is different between Sib 5/6 and 7, but once there it should be the same. So...
Sib 7: Go to Appearance > Design and Position > Lines (radio button). (See attached images)
Sib 5/6: Go to House Style > Default Positions > Lines (radio button).
In the dialog: Select Crescendo, in both Score and Parts, change "Vertical position relative to staff" from -5.5 to -4.5. Be sure to do the same for Diminuendo.
If doing this in an existing work in progress, you may need to select all, then Appearance > Design and Position > Reset > Position.
I went into my master .sib file and it was already set to -4.5, not sure how the VDL Template file got changed.
Let me know how you get on.
Hugh