First, let me tell that I'm a freelancer and don't belong/have a company and work on my own.
I have a big client that asked me for a cost estimate for a big project.
The project involves technical aspects that I don't master (nor want to, because of its size), but am really comfortable doing my part, so in this case I will have to get a technical parter (a company for sure, because of the dimension of the project).
The project will go on after I finish my part, and the partner I suggest will remain on the project doing the maintenance.
One important thing is that I don't want to (and can't) be the head of the project (because of the time I would spend on just one project, I wouldn't have time to other projects, and also because it would make me take all the responsibility from both my work and the partner's work (which I wouldn't mind, but the real problem is that all the payments, invoices and taxes would have to be supported by me, and not being a company is bad in this case)).
This means that there will be two suppliers, me and the suggested partner, each doing their job, as a team, but invoicing separately and having split responsibilities. I've done countless projects with this method and works well, the only difference is that in this case I am getting the partner.
Finally the question:
Is it ok for me to ask/request a commission (maybe a percentage of their cost estimate) to the partner I'm suggesting? (my logic is that I'm giving them a big project).
I don't want to be (or sound) greedy and first I need to know if this is the correct thing to do, and what could be the normal rates/percentages, and how to protect me in case they want to stab me in the back (like stealing the project from me).