Are Keysight 4145B setup files compatible with the Keysight 4155A/B/C or Keysight 4156A/B/C?

Yes, but check the format of your Keysight 4145B disk. If it is a 1.44MB disk (two sensing holes) the Keysight 4155A/B/C or Keysight 4156A/B/C thinks it is the older 750KB format. You get a format error when trying to read the setup files. Place a piece of cellophane tape (any office tape) over the media density hole and the compatibility problem is solved.