Is it permissible to expand the portion of 'Arafat which is specified for pilgrims to stand on so as to accommodate their increasing numbers?

Muslims are unanimous on the validity of standing on any part of the plain of 'Arafat due to the words of the Prophet who said, "I stood here; the whole of 'Arafat is a place for standing" [Muslim]. There is a consensus among Muslims that the hajj of someone who stands outside the boundaries of 'Arafat is invalid and he is therefore obliged to make up the hajj.

The ruling

It is impermissible to expand the portion of 'Arafat outside the boundaries over which Muslims are unanimous.