Can you bring your own cake in if you don't make a birthday reservation?

Yes u can bring a cake I am on the 6th. Hope this helped

They dont say to not but I would just do it.

Yes you can. They can keep it refrigerated if you need it kept cold.

I don't think there would be a problem but I would advise on making reservations when you can. Maybe talk to the staff when you get there for help with a surprise approach.