Switching Google accounts

Just to make my life more complex (hopefully simpler in future) I have decided all my email accounts will consist of three Google accounts, classified as low, medium and high priority. This involves two completely new gmail accounts and one existing one. At the moment I am working on switching over my default email account to one of the new ones (the low priority one) that is the catch-all account for all sorts of web site signups. It is quite a big process switching over Google accounts. The fact this blog is going up under one of my new accounts is part of the completion which has involved changing all the blogs over to two of the new accounts (I always have two author accounts on each blog). 
Some of the big steps undertaken have been transferring and deleting email, and downloading all the Google photos. Google does provide an email and contacts transfer functionality in Gmail that I used to transfer multiple accounts with, including my soon-to-disappear Microsoft accounts. As content has been moved, old content has been removed. The next step was to download 16 GB worth of photos from Google Photos. The reason there was so much stuff in there was that it included all my old Picasa photo albums, long since forgotten about, which evidently were migrated to Google Photos some time back. I currently use Flickr to host these photos and have not done anything with the Picasa stuff for a long long time. Consequently there are many duplicates of Flickr albums and these will not be going back up on the Google Photos of my new account, only the photos taken on the phone are planned for at this stage.

I had to use Takeout to get the photos (there seems to be nearly 100,000 of them) and use a download manager to pull down the nine zip files totalling over 16 GB. Apart from Picasa I also did briefly trial the Google photo uploader to backup my photos from my PC, this was abandoned when I realised it was just a backup tool for backing up photos from a PC, not a sync tool for public albums like Picasa was. I will have to find the phone photos and download them back onto the phone because resetting it (see below) has wiped them out. The biggest potential problem from downloading these photos is whether they will have an impact on old blogs, because Google stores blog illustrations on Google Photos, so if I delete my old account it does have the potential to remove the photos including possibly the ones that were used in blogs.

Next steps including migrating calendars and the Chrome profile and this will take some investigating and testing. I have also factory reset my phone to force it to use one of my new accounts so I have had to reinstall all the apps on it. There is still a lot of account migration work to do and it will be some time before I actually delete anything. But I did delete a very old Microsoft account going back about five years and it may well be the case there are still some very old Google accounts forwarding occasional emails that will come to light as this project progresses.