I would get onto Divvy for a looooooooooooooong appointment first, and then go to the authorities (with her...).

DH and I have been foster carers for many years, and have current Working With Children certification, up to date police checks, and all the bells and whistles so we'd have a pretty good case for why the baby should actually stay with us for the time being, rather than being disrupted and displaced again with another set of strangers ...

But for the child's long term benefit, to find out their biological history (particuarly as there might be medical things we as parents would benefit from knowing sooner rather than later) and so they can have a better understanding of their own history we'd definately go to the authorities.

We just wouldn't be handing them over without a really big fight...

Also, there would be the possibility that it wasn't actually the parents who dropped her on our doorstep, and on the off chance that there was some poor new mother going out of her mind because some deranged / vindictive / evil / temporarily amnesiac person had stolen her baby and run off with them (and then popped them on my doorstep) it would be incredibly shattering for me to be getting their child wrongfully ...

But if they were safe and alive but unfathomably unwanted by their birth parent, they could come and join our family

Wow - isn't it weird how you can get shown a situation like this and decide in under a minute what you'd do and why??

I wonder if we'd all answer differently if we were asked on another day, or in another mood??