When importing data, it uses a table called "xf_import_log". In this log, the system stores ID changes, paired between old IDs and new IDs. This is how the system rebuilds links within the system, whether they be forum IDs, user IDs, etc... This is a great system... there is however a problem. When you start a new import, it truncate sthe existing xf_import_log with a function called "resetImportLog". I do understand why this reset is important; if an administrator wanted to import data from multiple forums into a single forum, the reset would prevent ID clashes. However, at the same time, I would like there to be an option to skip this reset; in debug mode only if so required. Why? Because sometimes the information in a previous import is important for a subsequent import... such as user ID information.