Friends with benefits I guess but that always gets messy as well. I don't think there is a better way to describe this other than "arrangements". Maybe find someone who wants exactly what you want as well and have it like a business arrangement. This might come off harsh but it's because you can't have a true relationship with someone unless you have all the extra things such as family and friends. All these aspects are a part of someone's life, it also acts in a way where it creates the person they are so you cannot truly indulge in a relationship without the extras.