Hi Dan,
thank you so much for getting back to me. Luckily the keyframes were fine as linear, so that totally did the trick.
PS – I’m a complete noob with expressions, but I’m trying like crazy to learn them. Your website has been absolutely invaluable, so having you answer my question here on CreativeCow is a real honor. You da man (as we used to say in the 90’s).
Thanks again