A method includes tethering a first pop up branch structure of a tethered pop up branch structure stent graft to a second pop up branch structure of the tethered pop up branch structure stent graft with a tether. The tethered pop up branch structure stent graft is deployed into a main vessel such that the first pop up branch structure is near a first branch vessel emanating from the main vessel and the second pop up branch structure is near a second branch vessel emanating from the main vessel. A first guide is passed through a first collateral opening in the first pop up branch structure and into the first branch vessel. A second guide is passed through a second collateral opening in the second pop up branch structure and into the second branch vessel. The tether is then removed such that the first pop up branch structure slides outwards on the first guide and into a first ostium of the first branch vessel and the second pop up branch structure slides outwards on the second guide into a second ostium of the second branch vessel.
