When performing the search, you just need to locate what part of the tree structure you are inside, and filter the Ancestors-list by that:

.Filter(x => x.Ancestors().Match(a-b-or-f-page.ContentLink.ToReferenceWithoutVersion().ToString())

If a, b and f are landing pages of the same page type, you could do simething like this:

public static T GetParentOfType<T>(this ContentReference contentReference) where T : PageData
{
	if (contentReference.IsNullOrEmpty())
		return null;

	while (contentReference != ContentReference.EmptyReference)
	{
		var content = contentReference.Get<PageData>();
		if (content is T)
			return content as T;

		if (contentReference.Equals(ContentReference.StartPage))
			return null;

		if (content == null)
			return null;

		contentReference = content.ParentLink;
	}

	return null;
}

And then:

.Filter(x => x.Ancestors().Match(currentPage.GetParentOfType<MyLandingPage>().ContentLink.ToReferenceWithoutVersion().ToString())

Hi Tomas.

Thanks for your reply.

am getting below error.

the Ancestorsdoes not exist in the current context.

Ancestors() is an extensions method defined in the namespace EPiServer.Find.Cms.ContentExtensions

What version of Find are you using?