Hello, all. More questions.

We know that the Burrow has lots of magical enchantments on it. So does Number 12, Grimmauld Place. So if it's heavily protected, why are Fred and George able to apparate inside of the house? They first apparated on Ron's knees, if I remember correctly. Were other Order members able to apparate inside the place, too? Why is that?

And if you can apparate inside Grimmauld Place, can the same be done for the Burrow? Or do they have different enchantments on them?