S.H.
Even at the Mall... they WILL let you use your own camera... to take the photos.
THAT is what we do. We do that every, year.
We simply ask them, they say 'sure...' then my kids go and sit with Santa... and WE take the photos with OUR camera.
It is fine.
LOTS of other people, do that too.
They cannot tell you no.
Because that would be like 'forcing' you to purchase the photo.
All the best,
Susan