Yes. Send a note to icon@uiowa.edu with the course number and section numbers, and we can combine them into a single site for you. If you've already done design work on one of the sites, let us know which one, and we'll use that as the base site for all the sections.
When the sections (or courses) are combined, you'll be able to view your gradebook section-by-section using the dropdown menu at the top of the gradebook window.
If your TAs are accurately assigned to the sections in OSIRIS, they will be able to view grades for their sections only. However, if you want TAs to see other sections, let us know and we can adjust their access. Note that with the Classlist tool (different from the gradebook), your TAs will see the enrollment for all sections. If that's a problem, let us know and we'll help you find a workaround.