I am a 26 year old mother with a 18 month old son. Jacob, my significant other has a 17 year old "step daughter" that lives with us. She is his ex wfie's daughter that has a different dad. She constantly disobeys me when I try to set limits on how much care she can provide my son. She has taken him away from me when I have been playing with him. tries to tell me what to feed him, tells me i'm dressing him wrong. She continued to bathe him when he was infant when I asked her not to. She has even decided that she is going to potty train him against my will.