We really love Katharine, says David Foster's daughter for stepmother

It seems that David Foster's daughters have happily accepted their stepmother Katherine McPhee when Erin opened up about respecting her for having five adult stepdaughters, who are "older than her."

The 37-year-old daughter of David talked about the age difference at the premiere of 'David Foster: Off the Record' at the Toronto Film Festival on Monday.

"The truth is we really genuinely love Katharine," Erin told Us Weekly exclusively at the Elgin Theatre in Toronto.

"It takes a very strong, graceful person to come into a family as the fifth wife and have adult daughters who are older than her and do it in a way that really creates inclusion with the family, and she just does it effortlessly. She just makes it really easy for all of us to get along. So we're very grateful for her," said Erin.

Erin and her sisters -- Sara Foster, 38, and Jordan Foster, 32 -- are David's daughters from his marriage to model Rebecca Dyer from 1982 to 1986.

She also has half-sisters Allison Jones Foster, 49, who David and his then-girlfriend placed for adoption when he was 20, and Amy S Foster, 46, from the songwriter's first marriage to singer BJ Cook from 1972 to 1981, reported Us Weekly.

When asked if she's ready for another sibling if her father and his new wife go for, Erin happily said: "Anything that makes them happy, I'm happy with."

The film 'David Foster: Off the Record' is a documentary about David, an acclaimed songwriter who has worked with several renowned singers including Whitney Houston and Celine Dion.