Desperate for advice. I have a 13 year old and a ten year old. My partner of two years has recently moved into my home with a 16 year old son and 8 year old. My partner tells my children off all the time if they don’t follow my rules. Essentially he is backing me up, however his two have no real rules and he doesn’t tell them off at all. My daughter has restrictions on phone use - 16 year old doesn’t but I doubt my daughter will when 16 but he is allowed to sit with it whilst eating, ear buds in etc. We are arguing about it constantly lately as he won’t accept me challenging behaviour at all. He agrees rules with me and will enforce for my children but won’t his own. This morning his daughter wouldn’t allow my 10 year old to use her hair brush - they generally let each other use things all the time of each others and stood brushing her dolls (actually my daughters doll she has allowed her to play with all weekend) hair with it whilst my ten year old was crying about not being able to find another brush to get ready for school. My partner told my daughter off for being dramatic and making a fuss but the reality is his daughter was taunting her with the brush and enjoying her being upset and told off. Both children wrong to behave in this way but he sees no wrong in his daughter’s behaviour. He still maintains this evening his daughter was just being a normal child and not a big deal. We argued previously as he said I was a bully for not giving his daughter her desert as she refused to say please and thank you. Very basic rules of manners and I expect the same from my two. Blending is hard but my ten year old gives into his 8 year old all the time and I don’t want her to be resentful but me allowing behaviour in her that I wouldn’t in my child. But he really sees no wrong at all. She has taken her toys without asking and hidden them in her mums house and neither him or his ex wife have challenged is as they don’t think it’s a big deal. I am at a loss how to move forward.