I have three DC, two of whom have ADHD (12 yr old and 17 yr old). They were diagnosed about 6 months ago. I also have a 15 yr old.
I have two main issues at the moment. Firstly, it's a nightmare getting 12 year old to school in the morning (or generally get anywhere on time, or do any chores etc). I'm really really trying to keep my cool, talk calmly, put rewards in place for doing the things that need to be done etc, but it's still just a nightmare.
The second issue is sibling relationships. DC17 and DC12 currently have an awful relationship. DC17 makes it clear that she hates DC12. DC12 idolises DC17, but also winds her up massively (sometimes on purpose, sometimes inadvertently). They both genuinely think I let the other one get away with murder (I try to avoid "punishments" for both of them, and stick to "educating"/lecturing, with a bit of rewarding for good behaviour). DC12 also winds up DC15. DC15 and DC17 get on fine.
I'm just at a loss as to how to live more harmoniously, and also how to get DC12 to care more about other people and duties/obligations. Any tips?