Sorry. Newbie here. Picked up a client that needs has a blog through LexBlog. They want to recreate it on DreamHost and move all of the information over.She puchased her hosting through DreamHost and added the current domain. Then set up a mirror site. I have never used DreamHost or a mirror. Question is, will the mirror even work since the original site is hosted elsewhere? Or should a basic subdomain be set up to build the new site on before we make the switch over. 
Client has set up a mirror on DreamHost, but original site is hosted elsewhere
subdomain;dreamhost;mirror