Robinson, who died on June 5 at age 84, was reportedly romantically involved with Lucchese — and now a source tells PEOPLE they appeared "very open" about their relationship in the workplace.
"We all knew," adds the insider.
The source says that Scholastic staffers also knew Lucchese, 54, would inherit the company where she's worked for 30 years, describing it as an open secret in the office.
For more on the succession for Scholastic following M. Richard Robinson Jr.'s death and other top stories, listen below to our daily podcast PEOPLE Every Day.
"It was not a shock to me at all," the source says, adding that Lucchese — who is also Scholastic's chair of the board, executive vice president and president of Scholastic Entertainment — was respected in the office because she had his ear.
Spokespersons for Scholastic did not immediately respond to PEOPLE's request for comment.
A former Scholastic employee praised Lucchese to the Wall Street Journal, and said …