DH has a week away for work - I've stayed at home with all the SC's 23,22,21,15,13
We constantly have to remind them to lock the doors when they leave the house - lock it behind them when they come in and go upstairs etc. As they forget or cba. It's soul destroying. We both have expensive computers and other HW downstairs. As well as all the car keys.
I woke about 6 this morning and came down to find the kitchen window - which opens on to a side road - wide open!!!
No one will admit to either opening it or leaving it open. There was also a greasy pan in the sink - but the person who left it claimed he had agreed with another sibling that they would wash it. But it was obviously someone who had something to do with the pan who left the window open.
Partner has just sent a group chat message; replying to my group chat message; about how pissed off he is - and if they don't start showing some respect they should basically 'F' off and find somewhere else to live. (They haven't saved any money ever ) they also can't go to their mums due to her having issues)
They just spend their money on going out / take away / festivals etc
Last week we had an incident where the older kid came in drunk in the middle of the night - left the door open - a random kid walks in and falls asleep in the sofa and is actually physically sick on my throw!!!
How much more of a wake up call do they need? Or do we need...? 
The feeling of annoyance is almost giving me heartburn. I'm only the stepmum but I sometimes just want the older kids to either step up - and start saving for their own place and start acting responsible- or just go. I feel we are enabling this shit behavior.
I shouted at everyone of them this morning but they all blame each other and just go.. it does my nut in!