Hi,
Yes, you are correct, any parameters you create in the SOAP call will automatically get added to the Process DataSet if they don't already exist. If they do already exist, the values you pass in the SOAP call will be entered into the existing DataSet variables.
Personally, I prefer to create a placeholder for the Parameters that I will pass into a Process. This allows me to keep track of the parameters, plus anyone else who looks at my code will know what/where those values come from.
Normally I make a page in the dataset and call it Input Parameters, and then any parameters that I will be passing I list in there.
But that is just me, it is a totally optional step, as they will be created when passed from the SOAP call.
Thanks,
Ian