Consider the situation where a grandparent or other nonparent files a custody action against a parent. The complaint includes allegations regarding the relationship between the nonparent and the child and includes allegations that the parent has waived their constitutional right to exclusive care, custody and control of the child. In response, the parent files an answer and a motion to dismiss the complaint pursuant to Rule 12(b), arguing that the nonparent does not have standing to seek custody of the child. To determine whether the complaint should be dismissed for plaintiff’s lack of standing, does the court need to conduct an evidentiary hearing to determine whether the parent has waived their constitutional right to custody or is the standing determination made on a review of the complaint alone?