Peters, 26, popped the question to Roberts, 22, with a pink gold and diamond ring over the holidays in New York and the couple then welcomed the New Year in London.
While the 22-year-old's stepmother Eliza Roberts and grandmother Lila Garrett are "happy" for her, they admitted they were surprised by the news.
According to tmz.com, when Eliza was asked for her reaction, she said in a video: "I think I know what he's talking about. I don't know if these guys know."
She then proceeded to tell other family members that Emma is "getting married", adding: "We're very happy for her. If she's happy, we're happy."
Asked if she saw the engagement coming, she said: "I mean no, not really, but it's very romantic and if she's happy, we're happy."
Her grandmother added: "Of course (we're happy), I didn't know about it. As long as we don't see it going, that's the important thing."
--IANS (Posted on 10-01-2014)