So, DP trying to do the right thing by me. Said he will make DSD tidy her room but she's been here nearly 2 weeks and he's only told her that she will need to tidy her room up "soon". She has 10 damp towels in there already and you can't see her carpet! 
He said he wants to be fair to my DS and give his DSD an allowance instead of just dishing out the dosh (they are both the same age). I have given DS an allowance for about 7 years. However, he wants to give DSD an allowance of over 4 times what DS gets as she socialises more and he (we) will still buy all her clothes, toiletries etc on top. He has suggested that "we" match DSD allowance for DS and offered to pay half of my DS (we don't share finances). I just feel that yet again, DS and I have to change to suit the step children and HIS family. I'm sure DS will be happy to get a "rise" of over 4 times, but it's not because he "deserves" it or because I've had a pay rise, it's because DP wants to give this amount to HIS DD. Maybe I'm being unreasonable but I am so full to the brim of stress.
He is tip toeing round her like she's made of porcelain because she's vulnerable and upset (although showing no outward signs at all) so even if they live with you, it doesn't stop them being a disney Dad does it?
He was nearly in tears yesterday sending her to see her Mum for half an hour with other family members and tried to insist on waiting outside the house so she could "escape" if need be. Telling me he didn't really want her to go and that he was frightenened she might not come back. Then 2 hours later he is sending his ex e-mails asking to know when he is going to be allowed contact with DSS and telling me that DSS should be "made" to see him and she is being unreasonable.
Just needed to offload.