Brooke Mueller is allowing Charlie Sheen to see his sons because she wants more child support money.

The former actress has negotiated a fragile peace with her ex-husband and allowed him to see their four-year-old twins, Bob and Max, last Tuesday, but friends say the reason is because she is upset he has slashed her support money from $55,000 to $20,000 a month.

"There is only one reason why Brooke allowed the boys to go over to Charlie's house last week. She is desperate to have her full child support payment. Brooke is a smart woman and knows if she is in Charlie's good graces, he is more likely to give her the money. It has been very hard for Brooke to live on $20,000-a-month because she has to pay for her sober coaches and ongoing expenses related to her recovery," a source said.

Brooke, 36, has previously been admitted to rehab for drug abuse 19 times, and is not currently the official guardian of Bob and Max, who are looked after by her brother, Scott.

She is also said to be uncomfortable with her boys meeting Charlie's new porn star girlfriend, Brett Rossi. "Brooke doesn't like Brett spending any time with the boys, but knows if she fights it, her chances of getting the $55,000 go out the window," the source added.

Under the terms of the current custody agreement Brooke is allowed to stay in the house Charlie bought for her and the boys - where they currently reside with Scott - when she has visits, but is not allowed to live there. She is also said to be hoping Charlie won't go through with his threat to sell the home, in the same gated community he lives in. "She loves living in the exclusive community, even though Charlie lives nearby. The condominium Brooke is living in currently is very depressing and small. Under terms of the current custody arrangement, dictated by child protective services, Brooke's brother is the only person allowed to live in the mansion full-time," the insider added.

While he has called a truce with Brooke, Charlie has been directing his anger at another of his ex-wives, Denise Richards, last week calling her a "pig" with "cloven hoofs."