Shiloh, 22, from Coquitlam, was struck and killed in a vehicle collision while out for a walk near the British Columbia Institute of Technology (BCIT) on Feb. 17.
Ten days earlier, her younger sister and roommate, Keziah, died of undisclosed causes, according to posts on Shiloh's Facebook page.
Janica Lucas, a cousin of the two women, told CBC News that relatives are having a hard time coping with the losses that came so close together.
"It was hard enough losing one of the sisters," she said. "We were trying to deal with that and figure out how to cope. It's heartbreaking."
A GoFundMe.com web page aims to raise money for a memorial bench for the sisters. The page shows a picture of the two girls smiling and says, "Two beautiful sisters are no longer with us."
Today's memorial was held at Willingdon Church in Burnaby. Friends of the family, who organized it, say they're hoping it will help them push past the tragedy.
Burnaby RCMP say the investigation into the crash that killed Shiloh is a "high priority."