Okay, so I don't want to be nasty with this, so don't take it that way!
Cover: I really like the cover. It's simple but effective. 8/10 :)
Blurb: So, this is pretty short and sweet. I love the simplicity in this too. However, maybe slightly more information would be useful. Remember; the blurb is the way a potential reader decides whether to read or not, so you want to make it attractive and intriguing. Try adding in some questions. They usually work. :) 7/10
Plot: Interesting idea. But you have to be very careful when presenting a family reunion story. You have ensure you don't form the connection too quickly between to the two characters, but unfortunately you have here. I understand that they knew each other from school beforehand, but how would you feel if some kid you went to school with suddenly told you he/she was your twin brother/sister? You have to take the time to establish the relationship between the pair. That's really a general note for this whole Movella: take your time! Enjoy your writing! Take your time to explain how each character is feeling about this strange situation. And try to spend more time explaining the actually situation, as I got lost a couple of times. 5/10
Spelling and Grammar:~ Your spelling is pretty good to be honest, I didn't notice many major mistakes. Well done. :) Grammar, however, is something you need to work on. There is an easy cheat way to get around most basic grammar mistakes - Microsoft Word. Paste your chapter into Word before publishing it as an easy editing technique. Also, ensure to start a new line each time someone speaks. For example:~
"Marry, Dr Who starts in 5 minutes, this better be important!" I told my foster parent, Marry. "Well, I have something to tell you..." "What, Marry? It starts in 2 now! Better make it quick!"
Finally, make sure you use to correct version of the word (sorry, this is a pet hate of mine)!
To - "I'm going to the shops."
Too - "There are too many of them." or "Can I come too?"
Two - "Two cats are better than one."
You're - "You're going to the shops." (You are)
Your - "That is your cat." (Possession)
Their - "That's their cat." (Possession)
They're - "They're going to the shops." (They are)
There - "Look! Over there!"
So, for grammar - 5/10
So, altogether, that's an eight, a seven and two fives, which gives you a final average of...
Well done! Keep writing and I'll check back soon. :)