I would like to talk about my very elaborate work migrating 20 websites—20 so-called subdomains—to one main domain in order to have unified management for all of them. If I stayed in the old situation with 20 separate sites, I would have to maintain each one individually, which would require a lot of time, and some of them would eventually be forgotten. This would lead to unnecessary difficulties when problems arise.
In WordPress we have a very good possibility to unify all the sites under one management system, the so-called WordPress multisite. For this, however, I have to carry out several difficult tasks. I need to upload all my images—there are many of them—into their new locations and folders. Then I have to export the old database tables and import them into the right place within the multisite environment.
The situation has changed because the paths to the uploaded images are now different. All paths are subdivided within a single upload folder, organized by an intermediate folder called sites. Inside this folder each site has its own numbered subfolder, created by myself manually when I define a new sub-site in the multisite setup.
Transforming the old paths to the new ones has been the most difficult problem. Every method I have tried so far has both advantages and drawbacks. So I make mistake after mistake, and up to now I have managed to transform only two—perhaps three—sites to the new structure. But I will not give up. It is a large investment of time now, but it will save time later when managing and maintaining all the websites.