Hi everyone. I am currently in a blending situation, I came into the relationship with my son when he was the age of 1. My significant other entered our relationship with 2 daughters age 1 and 2 at the time. Our little ones are now 4, 4, and 5 and not long ago my significant other and I had a baby of our own. Since day one his oldest daughter has been a handful. She moved in with us pretty early into our relationship and from there the arguments between myself and significant have been constant and never seem to end and they're always over the same thing - his oldest daughter. His oldest has some severe and obvious behavioral problems and it was to the point during the school year there was rarely a day that went by where the school / her teacher was calling REGULARLY or she'd flat out be sent home and told she couldn't come back the following day. Him and I argue over the fact that I dont "mother" her the way HE feels is right. But like i stated earlier, she has behavioral issues and the way i go about parenting her is the way I feel I'd parent MY children if they were to EVER acted the way she does. She gets a kick out of breaking things and its rarely ever HER stuff but its more often than not my son, my daughter or own personal belongings from things I've had since high school that have sentimental value, to legit ruining soooo many of other items of mine, to breaking my kids toys. Shes loud all the time. She thinks everything in our home is hers. At this point, any and everything I say or do to try and correct her behavior I'm met with push back from her dad. It never fails. she also DOES NOT LISTEN. It doesn't matter how many times you punish her, take her toys, take her tv etc she just flat out doesn't care. In my situation its become extremely hard to form a bond with her. Shes literally in trouble or being told to stop doing something ALL day long. When shes around I legit feel as though I have to walk on eggshells to prevent from being accused or cussed over the "treatment" she received (per her dad). As i also stated earlier the school was continuously calling us about her behavior and has told her dad he needs to have her tested. I've suggested it and all he says is "im not putting my daughter on meds" which I completely agree with but at what point do we acknowledge that this child has an issue? I love her, but she is truly becoming annoying af and its becoming taxing to my mental health and feelings. Does anyone have coping methods or advice? Im struggling this point and just want to back off from the entire situation and allow him parent her without me being involved period.