Adoption

My partners daughter has been placed for adoption, we could fight it through the courts and a solicitor has advised that we have an excellent chance of winning, bringing his daughter up with her dad, the problem is is daughter's birth mother. She doesn't want her daughter, doesn't attend any offical meetings and has given up her parental rights! BUT says she would rather two strangers bring up the little girl than ME and daddy. My partner wasn't even aware he had a daughter until 6months ago when her 'mother' told social services he was her dad. Now we attend all meetings, email daily and have met his daughter a few times. My partner still has parental rights so do we ask the court to let her come and live with us or do we leave her with the people who want to adopt her. I have an 8yo son and we could bring her up no problem but my OH says birth mother will cause us nothing but problems, I KNOW he wants her with us but is just scared. I have no idea what is for the best!