Using CD InScriptOr to add sessions to an ISO9660 CD created on another system is not officially supported, but is believed to work in most cases. However, if the existing session was created under Mac OS, and you attempt to merge a new session with the existing one, this process will not work properly. This is due to the presence of "associated files" on the CD, corresponding to the Mac's resource forks.
If you purchased CD Writer Suite v4 from us, or have sent in a registration card for version 4, you may contact us for assistance by email.