By Jen Heger - Breaking Celebrity News Assistant Managing Editor

Randy Jackson has been pressuring his sister Janet to join their other siblings who've been plotting to overthrow the executors of their late brother Michael's estate, and Breaking Celebrity News has exclusively learned the reason why the reluctant Nasty singer agreed to participate.

Ever since Michael's death three years ago, Randy Jackson has been insisting that brother Michael's will was fraudulent, despite the fact that it was validated by a judge and withstood three legal challenges. The Thriller singer left all of his siblings out of his will and left everything to his three children and to his mother Katherine.

Longtime watchers of the Jackson family were stunned when Janet's signature appeared on a letter sent to the executors of Michael's estate demanding their immediate resignation -- it was also signed by Randy, Jermaine, Rebbie, and Tito. However, Tito has since publicly expressed regrets about signing the letter.

Janet had been reluctant to join her siblings, but finally relented "after Randy wore her down. Randy and Janet are extremely close, and he told her the only way they had any chance in succeeding in tossing the executors would be if Janet joined them since she is the most famous Jackson member. Randy believed that with Janet aboard, she would legitimize their efforts. Janet finally agreed because she didn't want to disappoint Randy, as he has convinced her that without her, they stood no chance," a source close to the situation tells Breaking Celebrity News exclusively.

The