Check out how the ink looks. Is it pen or pencil or...whatever. Reason being, if it is from a writing tool that will leave a heavier mark as soon as pen touches the article and as it changes in direction you should see ink being heavier than the rest of the flow of the line that is written...that is a good sign. Keep in mind that even a simple ink jet printer can emulate this so, does the autograph look just a little raised from the other ink on the piece? If so, that is good. Does it feel and look legit? Have you investigated who you bought the Christmas ornament from and the actual signature?
Where you able to zoom in on the signature in the attached photo? I could rescan it larger. Looking at the first pen mark on the 'H' in Harry it does start lighter then goes stronger. I can tell the date in the top corner is 100% ink pen, as you said, I can feel the difference.
The Christmas card did come from the Official KC & the Sunshine Band fan club. Last month they sent us a signed photo and back stage passes for a concert we are going to. I'll scan in the photo also.
Just a side note, a Christmas decoration will have some kind of colour to it and Christmasy snow wouldn't it? It is tricky. Like, it is not a picure or index card that has a Christmas theme? Is it a tree decoration?