DALLAS—Authorities have identified six people found dead in a suburban Dallas home in what police said was an apparent murder-suicide plot. The Allen Police Department said investigators believe brothers Tanvir Towhid, 21, and Farhan Towhid, 19, made a pact to kill their parents, sister and grandmother before killing themselves. The bodies were found early Monday by officers performing a welfare check, Sgt. Jon Felty said. “It appears that the two brothers had entered into an agreement,” Felty said. The victims were identified as Altafun Nessa, 77; Iren Islam, 56; Towhidul Islam, 54; and Farbin Towhid, 19. Felty said one of the brothers wrote a lengthy post on social media in which he said he and his brother had a plan to kill their family members and then themselves. He also wrote that all of his decisions were based on weighing pros and cons, including the decision to kill his family. …