What if you still want to convert Chessmaster OBK books to CTG?
FGCRWNEW which can convert opening books in FBK,CTG,MVS,Wchess and genius to each other. What you do is to convert OBK to fbk books. The use Fritz itself to import the books in FBK format. As far as i can tell though this method works only for Chessmaster 4000 to 8000. Even though chessmaster 9000’s books are still named OBK, there apparently is some change in format , and FGCRWNEW doesn’t work on them.