This user didn't write a biography yet. Mysterious, are we?
I've found most of the PSA's from Doctor Who the past few series to be rubbish and/or boring.
This one was a lot more subtle and enjoyable.
Quite an unsatisfactory 'ending' to be honest.
Only Curating Contributors and up can change an external once it's been added. You can post in the Edit Requests thread for a show's externals to be changed.
"Am I supposed to add franchises all between them"
You add franchise as a relation from the oldest show to each related show.
If you go to one of the related shows and click 'View all' you'll see that it shows the rest as indirect relations - https://www.tvmaze.com/shows/26535/90-day-fiance-what-now/relations