Ontario provincial police say Dellen Millard is now charged with first-degree murder in the deaths of Wayne Millard and Laura Babcock, with whom he had a relationship.
Mark Smich is also charged with first-degree murder in Babcock's death.
Millard, 28, and Smich, 26, are charged with first-degree murder in the death of Tim Bosma, who vanished May 6, 2013 after leaving home in his pick-up with two men after posting the truck for sale online.
His remains were found about a week later burned beyond recognition at a southwestern Ontario farm belonging to Millard.
Millard is also charged with forcible confinement and theft of a vehicle in Bosma's death.
OPP said Thursday they charged Christina Noudga, 21, with being an accessory after the fact in that case.
Toronto police are holding a news conference at 3 p.m.