Right now, that's the only method that can be used if you want comments separate from the field. After giving it some thought, here's one possible solution that lets you keep the comments with the field.
The compiler doesn't care about non-standard XML comments element so you could do something like the following. Declare the comments for the field in the normal fashion and then declare the comments for the auto-generated property/event in an <AttachedPropertyComments>
or <AttachedEventComments> element like this:
/// This declares the <see cref="P:MyNamespace.MyClass.SomeValue" /> attached property.
/// These comments are for the attached property itself.
/// <value>Info about the value</value>
/// <remarks>Some remarks about the property</remarks>
/// <para>A code example</para>
/// <code>Code goes here</code>
public static readonly DependencyProperty SomeValueProperty =
The GenerateInheritedDocs tool would then remove the AttachedPropertyComments/AttachedEventComments content from the field comments and add them as the comments for the related auto-generated member. Would that be acceptable? I'm open to suggestions.
Something like that wouldn't take long to implement so I could get it into the next release which I'm hoping to get out within the next week or so.