Many comments have been made on places to look for the Somewhere only we Know Specials/Epilogue but it seems that many are quickly shut down because of copyright issues.

They can definitively be seen via the iQIYI app with English captions if you sign up for VIP status (Search for: Unique Memory).  From reviewing the original publicity posters and other photos they were created to be a bonus for the VIPs of that broadcast channel.  The first episode definitely clears up many things from the main series.  The additional two specials end up clearing up and also bringing up additional questions for some of the other storylines.  Enjoy!

Some of the individual media viewing apps have an initial free VIP watching period but you have to pay otherwise.  Usually it's cheaper to pay for a longer interval [quarterly vs. monthly]  if they offer it.  Sadly that is how they offer some premium shows. 

You have to be signed up for VIP first.  Search for: Unique Memory

Not sure why but they listed them under "unique memory" instead of the name of the regular show. 

There are only three additional shows /specials.  They were meant to close the storyline of all the main characters.  Each concentrates primarily on one or two of the couples.   In the app they are listed separately from the drama as movies and each has a  different subtitle after the words "Unique Memory:" to differentiate them. 

Can someone be nice enough to let me borrow their iQiyi VIP

I'm poor :'v

YES you can switch the app to English.  

1) Click on the person icon on the lower right.   You will see the third icon down on the left is a capital A inside a box.  

2) Click on the box and the list of languages will pop up.

3) Click on English and a dialog box will pop up in Chinese (of course right!).

4) Click on the Chinese characters on the right and the app will restart in English.

Message me if you are still having problems with it.

Glad you were able to figure it out.  This specials/movies really help to complete each storyline.