Joe Raedle/Getty Images(PARKLAND, Fla.) — Nearly four months after a mass shooting killed 17 people at Marjory Stoneman Douglas High School, the class of 2018 will graduate and posthumous diplomas will be presented to families of the four seniors who lost their lives.Hundreds of seniors from the high school in Parkland, Florida, will be clad in caps and gowns as they walk across the stage to accept their diplomas during a private graduation ceremony Sunday afternoon at the BB&T Center in Sunrise, Florida.The ordinarily joyous occasion will be bittersweet for the senior class. Among the those killed in the Feb. 14 massacre were four 12th-graders who should have been graduating alongside their classmates: Nicholas Dworet, Joaquin Oliver, Meadow Pollack and Carmen Schentrup.Although the school plans to grant posthumous diplomas to the four seniors who were killed, it was unclear how many of those students’ families would attend graduation.Joaquin Oliver’s parents, Manuel and Patricia, said they will go to Sunday’s commencement ceremony with their daughter, Andrea. They said they never imagined they would see their 17-year-old son’s classmates graduating without him.“We had a lot of plans for our lives,” Manuel Oliver told ABC’s “Nightline” in an interview Friday. “These kind of events destroy any plan that you had and leave you in an empty space with no plan at all.”The alleged gunman, Nikolas Cruz, a 19-year-old former student at the high school, is charged in connection with the 17 deaths as well as the wounding of 17 others, for which he faces the death penalty. The teen’s defense attorneys have said he will plead guilty “in exchange for a waiver of the death sentence” and a getting instead a sentence of life in prison.The seniors will wear specially-designed sashes over their graduation gowns that read “MSD Strong,” according to ABC affiliate WPLG.Dillon McCooty will also be wearing a graduation cap adorned with an image of Joaquin Oliver, his best friend.David Hogg spray painted his cap bright-orange and attached a $1.05 price tag — a jab at Sen. Marco Rubio (R-Fla.) and the National Rifle Association (NRA). The price tag reflects the amount of money that Rubio’s campaign received from the NRA, divided by every student in the Sunshine State.According to WPLG, all graduating seniors of public schools across Broward County will also receive an “MSD Strong” ribbon lapel pin to wear during their respective ceremonies.Copyright © 2018, ABC Radio. All rights reserved.