50 Cent has paid big money to support his son, Marquise. But the rapper never had an official arrangement with the boy's mother, Shaniqua Tompkins, and now he's taking the unusual step of making it formal, filing papers in Family Court here under his given name, Curtis Jackson.

One friend of 50 tells us he made the move after Tompkins started to get more demanding.

"It was just getting so out of hand," said the buddy. "It was driven by greed. He felt it was necessary to get a court order making clear just what his responsibility is. He took matters into his own hands. It's usually the woman who files. But he wants to do the right thing.

"He's paying a lot of child support. He takes [Marquise] on vacations. He just took him to L.A., where they saw Eminem together. He met Justin Timberlake and Timbaland in Miami. He took him to the NBA All-Star Game in Vegas. He sees his son very frequently. When he's on the road, he brings him out."

Felder would say only: "Ms. Tompkins is going to get more than fifty cents, I can tell you that."

The performer's spokeswoman, Cindi Berger, said, "Curtis puts his son's needs first. His son is well loved and taken care of. Anything else is a private family and legal matter."

Labels: 50 Cent