A branch stent for implantation from a main blood vessel in a plurality of branch blood vessels having respective branch blood vessel diameters, the branch stent comprising: a tubular element having: an axis of elongation; a first and a second tubular element end; the tubular element covered with a tubular element cover; and a parachute element having an unconstrained flat-toroid/disc configuration, the parachute element having a parachute element cover, the parachute element positioned perpendicularly at the second tubular element end, and positioned coaxially to the axis of elongation; wherein the branch stent is implanted from within a fenestrated stent-graft having oversized fenestrations, the fenestrated stent-graft first implanted in the main blood vessel at a bifurcation zone including the plurality of branch blood vessels, with each of the oversized fenestrations having respective diameters larger than respective branch blood vessel diameters; wherein the branch stent and the fenestrated stent-graft are together a multi-stent.