RootsChat.Com

The problem with non-microsoft software is that it tends to conscientiously use a different piece of jargon for the same thing, so the word 'backup' does not appear on Thunderbird's menus. If I remember correctly 'Archive' just files the older emails separately but still within Thunderbird. You might find 'export' does what you want, just remember to put the resulting file somewhere you can find it, and repeat the process at intervals. On my Thunderbird, archive is on the Message menu and export is on the Tools menu but your copy will be more uptodate so they may have been re-arranged!
Having said that, I let Windows (10) backup my emails etc. using 'Backup using File History' (which it offers as an alternative to 'back up files to Onedrive') You have the option to add a folder, so you just tell it to back up your thunderbird profile which can be found at C:\Users\User\AppData\Roaming\Thunderbird\Profiles . There may be a choice of profiles - I seem to be backing up the one with a current date.

Was there probate for the mother? It is usual to give full names for children who are mentioned in a will.

I have had it do that intermittently for a while. However I have found that if you are trying to fill in an empty box it is more likely to freeze at only a few letters. Whereas if you fill in the new name in front of the old name and then delete the bit you don't want it is more likely to work. (Windows 10 with Firefox )
I hope that helps.

They married in Wrexham. The other Bangor would be nearer. (Bangor on Dee/ Bangor Isycoed) Perhaps her husband filling in the 1921 just assumed it was the bigger place. Where did she say she was living on the marriage certificate?