found the fix. (Or: I found someone with knowledge in functions and actions in WordPress).
Yes, it was my mistake thinking this forum would be a good place to get help in solving problems related to coding in WordPress and Woothemes Canvas.
Duncan told me (after I asked this: “It seems that is not possible to include php into the hook system of Canvas… Any idea who could help making this possible?”):
“If you are not a member, this is exactly the kind of question that being a member of the Academy is about. Please consider joining here: http://jamiemarsland.wpengine.com/academy/. Our members tell us that the Support Forum is very useful to them.”
So I joined but I do have to say it is not as helpful as it was suggested. I expected a more busy talk around here and faster replies. No offense ment, I am happy with the input & the help I get from you Jamie, just expected something else in here.