I have a 7 year old little brother, and there are MULTIPLE ways...
- The best thing to stop an annoying sibling is to threaten them. Not major, but minor stuff such as the continuous nagigng of, "I'm not going to give you your gameboy unless you stop bothering me" Or "Stop or else I'm going to lock your computer!" Same applies for their toys, manga, etc etc.
- Get them to do things you want to do. For example, your mom asks you to take care of your little brother/sister. It's time to go home from the park when he/she complains and doesn't want to go home. Just simply instead of asking them to go home, say this, "I'm going to go home and eat ice cream...but I'm not going to bring you." They'll follow you either by, "Oh please take me!" or "If you don't take me, I'm going to kick you!" Act all annoyed and take them. =3
- ALWAYS have something to blackmail. If you don't, make one up, such as repeatedly singing, "I know who you like~~~<3" OR "Stop or else I'm going to tell you-know-who about the you-know-what." <- That part often affects bratty kids, not TOO young ones or the kids who know better.
- The easiest way for me is just to simply glare in a pessimistic matter at them, and say slowly "I'm going to eat you alive." <<; Works half the time for me.
...more. XD
*note: not all of these will work for you. Just something out of Lily's boredom and imagination. o.o