'double' nest form fields with accepts_nested_attributes_for


Is it possible to 'double' nest form fields with accepts_nested_attributes_for? Something like: [code=ruby]<% form_for parent do |parent_form| %>   <% parent_form.fields_for parent_children do |parent_children_fields| %>       ...          <% parent_children_fields.fields_for parent_child_activities do

parent_child_activities_fields| %>

             ...[/code] Rough example but should be enough for demonstration. What I'm trying to do is form a many to many join between parent and child while simultaneously creating a join to their activities. A parent has many children. A child has many parents. Parents and children together have many activities.

If this would be possible it would be a wonderful thing, though it depends on creation of the first level join before the second. Anyone have experience of this?