model creating a model?

hi all,
is it possible for a model to create an object (of which it has many),
when it is first created?
i'm trying to have something like

Image -hm-> ImageThumbs
where the first ImageThumb is created when the Image object is saved,
and any validation errors from ImageThumb.validation are passed back to
the original object/page template.

any thoughts on this?
thanks for reading.

This is entirely possible using a before_create, or creating the associated object along with the original object and using validates_associated :associated_objects