I want to run a new return on an addition to my house (new heat was added but no new returns!). I want to pan out along joists to the new section, but to get from where I want to connect to the return trunk to where I want the return register, I need to shift along the route from one joist to its neighbor. Is there an existing connector out there to do this. Essentially, I want to drop down, over and back up to the neighboring joist.

thanks for any help