Hi,
If you want to use SimBrief's internal random load generation logic then you need to either disable capacities in your fares (so phpvms can not generate any load) or you can disable pax, baggage and cargo amount transfer in SB form (so phpVMS will be able to generate but not send anything to SB)
In any case there will be a mismatch between SB and phpVMS. Also there may be logical problems, mismatches in your phpVMS financial data.
You may need to check SimBrief API documentation to better understand what to disable and how it behaves, also you may need to alter simbrief_form.blade.php if you want to select the second option.
Good luck