Hi there,
Congratuations on your plans to move in together.
My partner and I have been living together for just over 6 months, he has 4 kids, I have 1.
The main thing I would suggest is that you sort out ground rules before you move in. I thought because we all got on OK before we moved in, that everything would be fine - but it hasn't been!
Having a new home for all of you is a good idea as you can easily make new rules for all the children rather than one set feeling put out that they have to change just because they have new people living with them.
Talk about who will be doing what for who. Neither of you should feel put upon as this builds resentment. Don't expect to feel the same for your step sons as your own sons and you will have to work hard to make sure you treat them all the same despite this. Will your partner be able to do the same for your sons?
With things like the biscuits / TV example you have mentioned, I would suggest a compromise and talk to DP about it now. Could the other boys be allowed a tv in their rooms but have strict rules on when they are allowed on, perhaps all the boys could have 1 biscuit a day rather than several?
Listen to any gut feelings you have now and discuss them with your partner.
The biggest issue for us has been discipline - I don't feel I should be the disciplinarian for my step children but they should show respect for me and gradually as time goes on, they will accept that I am able to discipline them more as I have earnt that right. DP seems to struggle with treating my son the same as his own children and I feel that DS is treated unfairly sometimes and DP seems to think that his short temper with DS is "discipline" and I feel piggy in the middle between my son and my partner which is not ideal and builds resentment as I feel I am giving so much of myself to his 4 children, while also not having to stick up for my son.
I also really miss quality time with DS as I am now split 5 ways. I have started making time to just be with DS and I feel happier for doing so.