Catalyzes the addition of a phosphoethanolamine (pEtN) moiety to the outer 3-deoxy-D-manno-octulosonic acid (Kdo) residue of a Kdo(2)-lipid A. Phosphatidylethanolamines with one unsaturated acyl group functions as pEtN donors and the reaction releases diacylglycerol. a 1,2-diacyl-sn-glycero-3-phosphoethanolamine + alpha-Kdo-(2->4)-alpha-Kdo-(2->6)-lipid A = 7-O-[2-aminoethoxy(hydroxy)phosphoryl]-alpha-Kdo-(2->4)-alpha-Kdo-(2->6)-lipid A + a 1,2-diacyl-sn-glycerol a 1,2-diacyl-sn-glycero-3-phosphoethanolamine + alpha-Kdo-(2->4)-alpha-Kdo-(2->6)-lipid IVA = 7-O-[2-aminoethoxy(hydroxy)phosphoryl]-alpha-Kdo-(2->4)-alpha-Kdo-(2->6)-lipid IVA + a 1,2-diacyl-sn-glycerol Inhibited by calcium concentrations higher than 1 mM. Belongs to the phosphoethanolamine transferase family. EptB subfamily.