[Pottus]

I'm not going to say not use YSI for a login/reg system or uvars but I'll give you some friendly feedback with my experience with using it. I was using it at one point and it works fairly well but eventually some issues came up such as difficulty modifying data associated with uvars directly and sometimes the system would bug out preventing users from logging in. Now back to your problem I'm going to suggest using the user system that comes with YSI and also advise against using OnDialogResponse() there is a far superior way in the YSI system that is y_inline/y_dialog read about it here https://sampforum.blast.hk/showthread.php?tid=295049.

Now with that aside I'm going to recommend doing your system completely in MySQL or SQLite.