In presentation - http://www.slideshare.net/veosotano/axr-presentation-betabee... - slides 12 and 13, including new elements creation (http://axr.vg/spec/chapter/55). Didn't find anything on parent property in spec, though. Nesting is also planned (slide 15)

Sorry about that. It's not fully fleshed out yet. Are you interested in helping us figure out how to make the reparenting syntax as nice as possible? If so, I think the mailing list would be the best place for that... :)