It's not unusual for sisters to be sharing clothes and exchanging secrets one day and shouting at each other about how they each wish they were the only child the next day. Sibling rivalry, which is the jealousy, competition and fighting that occurs between siblings, happens in almost every family with more than one child -- and will often even continue as the siblings mature. In fact, according to a March 2008 article in "The New York Times," because sisters are more likely to have a closer relationship as adults than other sibling pairs, there is more opportunity for conflict and rivalry to continue into adulthood. While you can't make your daughters get along 100 percent of the time, you can help them resolve their sisterly conflicts.
Attempt to allow your daughters to work out their own conflict, stepping in only when it’s clear to you that their problem-solving skills are getting them nowhere, notes the University of Michigan website. For example, if your daughters are arguing over who gets to use the car on the weekend, try to let them come up with a plan of action on their own. If a solution isn’t occurring, try stepping in and offering a solution or an ultimatum, such as they need to figure this out with maturity and respect or no one is using the car on the weekend.
Separate your daughters until they calm down enough to work through their issues without fighting, advises Carl Pickhardt, Ph.D., Texas-based psychologist. For example, if they are fighting over whose turn it is to use the computer, send them both to their respective rooms for a few minutes with the instruction that they are to calm down and return to discuss the situation like adults.
Make sure you hold both girls responsible for their behaviors. According to the University of Michigan website, it’s a moot point who started the argument since they both decided to participate in it. Not taking sides can help resolve the conflict. For example, if Jane says that Jill started the fight and you get on Jill for starting it, Jill might not be willing to resolve her conflict with Jane because she feels that you are taking her sister’s side over hers -- and not being fair. Remain neutral.
Stay calm and acknowledge the feelings of both your daughters. Encourage them to sit down with you and ask them both to discuss – calmly – why they feel the way they feel. Don’t belittle anything they have to say and require that they keep their words and tone respectful. This allows them both to say what’s on their minds and work through their problem with maturity. Additionally, it provides a good example for how they need to resolve future conflicts.