Best Friends for Life

Sorry I haven't posted for a REALLY long time!
Anyways, Best Friends for Life is about three girls, Sierra, Juliana and Avery. Sierra's in third grade, Juliana's in 4th and Avery's in 5th. Sierra and Juliana have known each other for about a year and Avery has known both of them for about three months.
 In the beginning, things were working out pretty good. The three of them really got along with each other until... there was a huge argument between them.  At first, Avery thought that everything would be fine the next day but it wasn't. Instead, Sierra and Juliana started back talking and tattle-tailing on each other. Before long, Avery soon got sick and tired of them complaining on each other and tried to stop the fight.
So, the day they had their first sleepover with each other, she tried to sort things out between them. Will Avery be able to save their friendship?