ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / MapMemberCreationParams Class / MapMemberIndex Property

MapMemberIndex Property
Gets and sets the index of the MapMember in the map or group layer. MapMemberPosition must be set to MapMemberPosition.Index for this value to honored. Defaults to Auto arrange index position if MapMemberIndex is not set.
Syntax
public int MapMemberIndex {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 3.0 or higher.
See Also