Past year I build a site for a yearly conference event. http://reunionterapeutica.gtpbarcelona.com/
The 2015 event has done yet. Now the client wants to archive the 2015 event content in a folder or subdomain that can be visited by users, and use the root domain for the information of next year conference, and every year the client wants to do the same.
I have not considered this use when I build the site past year. So maybe I would had to consider other development strategies from the beginning.
So, which strategy would you use for this case of sites? When the same theme and structure will be used every year, but part of the content will change (dates, program, speakers, venue, organizers....), and also using WPML plugin because the site is multilanguage.
It's multisite the best method? There is another approach that could be also useful?