[eluser]theprodigy[/eluser]
when you post the new company that is created, is it possible to also post the user_id, so that you can populate the sec_companyaccess table as well? That will solve all your problems.
If you are creating a new user, then the only option I can come up with is to create a blank user row, and return the new user_id, then send to an edit form (thus having blank form fields, but already having a user_id).
Otherwise, you may have to re-work your site to the way I described before (create a company elsewhere, use the user-form to just assign the company to them - using a drop down to assign the company, or checkboxes to allow assigning multiple).