Bedtime moments

So I just got done reading a book by Nicholas Sparks. ( I love his books, all of them, and his movies). This book was actually a memoir called Three Weeks with my Brother which he wrote with his older brother Micah. In this book, Nicholas mentioned that his mom would come into his room at night and ask him to tell her three nice things that his brother and sister did for him that day. She also did this to both Nicholas' brother and sister. He said that at first it was hard to think of those three things, but it got easier night after night.
That really stuck in my mind. Lately it seems that my kids seem to be fighting or not say nice words to each other and that makes me sad. I always tell my kids, "friends will come and go throughout life, but brothers and sisters will always be there, no matter what." I truly believe that but.. that begins while they are young. If kids grow up fighting and not talking and not being nice, they will grow up hating each other and never talking to each other, and being alone.
 I know this first hand. I do not talk to my brothers and sister. It hurts me everyday. I don't know what happened but I don't want my kids going through the same thing.  And I use me as an example and they know it hurts me.
Tonight I decided that I am going to ask my kids, all five of them, to tell me three nice things their siblings did for them today. I don't care if it was a huge thing or a little tiny thing. Tonight being the first nice, it was hard for them. I told them I was going to ask them every night. Every single night and to be ready. I also challenged them to go the extra mile and do something nice for their siblings. I will keep these confidential. I will however write them down so I can have them to look at later maybe show them sometime in the future, if needed. 
It was cute what they thought of. It was also an eye opener to listen to them talk about that one nice thing that was done to them. I hope my kids will feel the love of the person being nice. I see this little bedtime moment I have the privilege being a part of going beyond what I am trying to do. I don't really know what I am trying to do except showing my kids we can live happily when being nice to each other.