An insert in a Design Option cannot be hosted by an element in another Design Option [--if you continue it will not be added to the design option set].
Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 26.2.0.0 (26.2.0.0)
Syntax
C#
public static FailureDefinitionId ConfusingHostByElementsInAnotherDesignOptionWarn { get; }