BP?
I'm not going to give you my opinion on weather is right or wrong for someone to hide a pet from a parent...believe me, I've tried...pet rats..kittens..garter snakes...but they don't stay hidden for long. At most they stayed hidden for a few weeks... live and learn i guess : )
Anyway...I what I'm getting at is the most important thing is that the snake gets proper care. I would make sure the enclosure keeps the proper temps. and humidity as well as provides enough circulation before you bring her home. Lighting is not usually an issue with BPs. Also, be careful to check for drafts on the floor or near a window. Respiratory infections can set in quickly when their environment isn't to par not to mention the stress from moving.
Is there a better option for the snake?