DC is listed on IMDb as creating the characters.
![Huh [hall2_huh]](http://www.dsboards.com/SMF/Smileys/classic/hall2_huh.gif)
I suspect that will come as a surprise to the estate of Art Wallace, who created every character up to Barnabas (and there's even a court ruling to back that up). But then, who knows who even added that credit to the site...
As for fitting in a sequel (or sequels) to a successful film, projects with an already established audience are hotly desired commodities in Hollywood, so stars, directors and studios manage to find/work out ways to do them. For example, considering his schedule is always so full, I suspect Depp already had several films in his pipeline before it was decided to do the first two Pirates sequels, yet they were quite successfully shoehorned in.
![Wink [hall2_wink]](http://www.dsboards.com/SMF/Smileys/classic/hall2_wink.gif)
With Burton, though, it isn't always the case that the same director helms the sequels...