Charlie Sheen -- Brooke Mueller Wants Cash For Kids ... That's it

Charlie Sheen's legal team is headed for court this morning ... and he wants to expose what he believes is a crass ploy by ex-wife Brooke Mueller to make her brother the guardian of their kids so she can still get her hands on Charlie's gigantic child support checks.

As we previously reported ... Brooke is gunning to wrestle temporary custody away from Denise Richards, who has been caring for 4-year-old Bob and Max while Brooke tries to get it together at The Betty Ford Center. Brooke wants her brother to get temporary custody until she's sober again.

Charlie believes the almighty dollar is at the root of Brooke's ploy. He claims Brooke will still have access to Charlie's $55,000 monthly child support check if her bro gets the kids, and that's why she wants Denise out of the picture.

What's more ... sources connected to the case tell TMZ ... Denise has written proof -- in the form of text messages -- in which Brooke makes it clear -- she wants and needs those monthly checks.

Sources say Brooke -- through her lawyer -- will counter that Denise is the one who is in it for the money, although our sources say Denise has not asked Charlie for a dime for taking Bob and Max.

We're told Charlie wants Denise to keep the twins until Brooke is sober and able to prove she'll stay that way. Charlie realizes that could mean Denise could have the kids for a year ... and maybe longer. Charlie will tell the judge he would gladly pay Denise support money for her efforts.