Advice please - dc non-stop arguing

[Jemster]

I have ds 6 and dd 2 and just recently (since dd turned 2) they have began to argue and fight. It is almost constant and over everything, toys, tv programmes, food etc.
Whatever ds has, dd demands it too and it's not always appropriate for her to have it. Me and dh find we are starting to just give her what she demands to avoid the screaming that will otherwise follow. She takes ds's toys which he hates and she screams at him if he changes tv programme. We sometimes let him use the i-pad and now she screams as she wants it and tries to push him off it.
DH and I very stressed about it and it's not making for a happy house.

Please can anyone help or give me some advice as we just don't know what to do.

No help but I'm interested in any suggestions too. I have DS 9, DD1 6 (7 this month) and DD2 3. We have exactly the same issues with DD2. Unfortunately we did used to give in for an easy quiet life but ins we haves mini dictator who thinks she runs the house. We are trying to reinforce her place in the pack (at the bottom, just above the 2 dogs)

Its hard isn't it. We too have a mini dictator, she is such a madam and just screams when she doesn't get her way. It's been going on all morning and me & dh are already fed up!