Florida Statute 61.30(3)(f) allows a deduction for court ordered support for other children that is actually paid. In addition, Florida Statute 61.30(11)(a)(11) allows a court to deviate from the child support guidelines for "any other adjustment that is needed to achieve an equitable result which may include, but not be limited to, a reasonable and necessary existing expense or debt."
These statutes have been interpreted by the courts through the Smith case, Speed case, and Flanagan case to mean that a court must consider preexisting support obligations to other children in determining the amount of support obligation for the paying parent.
In Lil' Wayne's case, under rules of Florida family law, he would be entitled to have a Judge consider his other support obligations for the four other children in determining how much he should be paying in child support for his fifth child. Be sure to contact an expert Florida divorce attorney for advice on how the support of other children affects the Florida child support guidelines in your case.