As a former employee, let me give you an illustration of how strict and completely backwards Disney is with copyright...
I worked on the Disney Wonder (ship) and was a part of the programming team (aka, kids' entertainment/childcare/whatever). I worked with 8-9 year olds. During free time, a lot of kids liked to color on coloring sheets of characters. So, I decided to enlarge our inventory of coloring sheets. Using a Disney computer on the ship and a Disney drawing program (that kids used), I printed off several characters including the Pooh and Friends characters. I was told I could no longer do that because those images hadn't been approved by the marketing department for use on the ship. So not only can non-Disney people not use Disney materials, Disney ITSELF can't always use Disney materials if you're not in the right place. Yes, completely confusing, completely insane, and completely my point.
However, on a side note...part of our programming included teaching animation. As part of the history, we got to trace back the changes in the characters over the years. Obviously, old versions are copyrighted as well. So, when deciding what to change on Tigger to make him 'okay', make sure you look at any possible "past versions" as well.
A suggestion? Think of using a different view point. It might be a lot easier to pass a back view of Tigger for example. Any old orange striped tiger from the back could be made to look like Tigger, or at least be a representation of him... That would probably mean you'd have to change your design a little to make a "scene" with him in it...maybe looking for a cache?