The eighth argument evolutionists should avoid is that "common design means common ancestry".
This is ridiculous. Common design is not the only evidence for common ancestry, and so trying to refute just this piece doesn't truly yield any results. There is tons of other evidence, apart from homologies, that confirms common ancestry. If we ignore the DNA evidence alone, there are some creatures in different branches of the tree of life that evolved similar features but don't share a recent common ancestor. Oi.
Instead of listing all of the individual pieces of evidence for common ancestry, I'll just link you to this Talk Origins page.