I’m assuming a lot of people replying haven’t had a blended family or tried blending a family judging by the responses 🤦🏻♀️
I have been in your position, our girls were 6&7 and got along famously well and were so excited when we all started spending time together but as time went on and we moved in the girls started bickering-I also did what you did and told my daughter off as well when she did nothing and it just made it worse. you do have to remember that kids do unfortunately argue though it will never be perfect unfortunately 🤣 Don’t tell them off if they’ve done nothing wrong though. This behaviour though is jealousy plain and simple and probably a bit of them thinking you might be replacing mum or being pissed off that mum and dad aren’t back together, or maybe is mum drip feeding them some rubbish too? .
We started ensuring that we each spend time together with our kids alone on “date nights”as well as a family time and also created some family rules together. It would be helpful to lay out that whilst you’re not their mum and he’s not your kids dad, you are both adults and you will both be respected if you were their parents. You need to show that you are now one unit. Also, when you’re doing the family rules then also discuss what happens if they do something wrong, tell them they will be called out on it by whichever parents then agree with them what they think is good consequences for bad behaviour then you can both enforce it.
I'm happy to say we’ve all been a family for 7 years now and apart from that short time (approx 6 months) when the girls were younger and bickering we’ve been wonderfully happy and now the girls are self proclaimed “best sister friends” and they do everything together, they are like the bloody twins from the shinning 🤣
Honestly blending two families is hard, it’s hard work and it takes commitment, patience and heaps of love. You’ve got to make the commitment to love your stepkids like they are your own and not resent them for being kids-remember kids only behave badly for a reason, usually because they have big feelings they can’t articulate or handle.
All of this said though, your partner needs to be on the same page. You need to have a separate conversation about how you expect you and him to be a team. Me and my husband had exact opposite thoughts about how to raise kids, I’m “firm but fair” and he’s a total “gentle parent”, we had to have a discussion about how to be a team, what we thought was good about our approaches and what we thought was fair ways of dealing with things, what our boundaries were when it came to parenting our children, so many things! Basically-sing of the same hymn sheet. And tell him that if he’s got to have your back, if someone’s getting told off then you have to be united. If he’s not emotionally intelligent enough to understand and participate in this conversation and act upon what you agree then he’s not the one and nothing you do will change your situation and everyone will be miserable and annoyed. If he’s committed to this and you become a team there’s no reason why you can’t all get through this and be where we are 7 years down the line :) good luck op!! X