Marina Krim's three children Lulu, six, Leo, 20 months and Nessie, three. Picture: Supplied

In an uplifting essay published on Sheryl Sandberg’s new community website optionb.org, she claims six-year-old Lulu and two-year-old Leo have sent her a “message” of love to help her grieve, the New York Post reports.

Marina Krim's three children Nessie, three, Leo, 20 months and Lulu, six. Picture: SuppliedSource:Supplied

The pair was found stabbed to death at their Upper West Side apartment in October 2012 at the hands of their nanny, Yoselyn Ortega.

Mrs Krim, 41, describes how, as the weeks and months went by after the killings, something “magical” happened.

Nanny Yoselyn Ortega appears in court. Picture: SplashSource:Supplied

She became hypersensitive and began noticing things such as street art — a stencil of a young boy holding a sign filled with colourful hearts, for example — that instantly linked her to Leo.

She felt that “maybe the universe was trying to tell me something, that it was helping me to realise that there was a beautiful ‘new’ relationship waiting to be developed with Lulu and Leo.”

“Over the next few weeks, my senses were awakened. I started noticing other connections,” she said. “One quiet morning, I was walking along the beach and the Peanuts theme song, a family favourite that was played at the kids’ memorial service, was blasting from a beach house.”

Marina and Kevin Krim are pictured with their daughter, Lulu. Picture: SuppliedSource:Supplied

She goes on to describe how a jogger stopped her and her surviving three-year-old child, Nessie, on a beach and said: “You and your daughter are extraordinarily beautiful.”

“Surprised, I thanked him and he jogged away. I really loved that simple message from a stranger. I wondered if somehow it was being delivered from Lulu and Leo,” Mrs Krim wrote.

The mum and her husband, Kevin, have set up a foundation, choosecreativity.org, in honour of their lost children.

In the Option B essay, Mrs Krim recalls how, on the first Mother’s Day after Lulu’s death, she had an idea.

The building where two children were stabbed to death allegedly by their nanny in a family's Upper West Side apartment in New York. Picture: GettySource:AFP

“On our last vacation together, Lulu and I had collected dozens of large sand dollars (a form of sea urchin),” she wrote. “I spent this Mother’s Day hanging up those sand dollars for display on an empty wall in our apartment. It was a simple way to express myself, feel present, and connect with Lulu and Leo on a really tough day.”

The Krims have since had a fourth child, named Felix.

Ortega is awaiting trial.

This article originally appeared in the New York Post