He will do the "commercial" support, but since it's still a very early phase in the project, the final customer isn't expected to use the admin interface itself

He will do the "commercial" support, but since it's still a very early phase in the project, the final customer isn't expected to use the admin interface itself, we'll do it. And by "we" i mean "I". So basically, he'll forward the customer requests to me. Do you have an idea of a "normal" commission ? I was expecting something between 10% to 20%