Adding a new Variable to control structure in DReyeVR

Hello everyone,

I would like to further customize DReyeVR for my experiment, I believe I will need to define a new variable from pythonAPI that can be accessed from the server inside control,

for example control.customVar = 0;
this variable can be accessed from the caralawheeledvehicle blueprint or egovehicle blueprint 

any idea how to tackle this problem ? 

thanks