I saw that pic and can tell you the two on the right are sisters just based on their identically shaped, but different sized, legs.
Scroll down the article to the vintage photos. Scroll to pic 6 of 10. Class photo from 1971.
Merkel - smack dab middle row, middle.
2nd girl - middle row, 4th from left behind boy in jacket.
3rd girl - middle row, 4th from right, her head is in front of door windows.
There is no indication of who the other 2 girls are.
http://time.com/time-person-of-the-year-2015-angela-merkel/