Can a change be made to a petition filed in Family Court?

A petition was filed for custody of a 16 month old child. Included as a reason for custody to be granted was information shared by another party (heresay) who orginally agreed to come to court for support of this information. Now they are "not sure" this is true. Can an amendment be made to exclude that information so that there is no cause for a slander/ libel case later?