Hi my name is***** am reviewing your question and will reply ASAP.
I can help you to configure the new account as a new Apple ID across all of your devices.
The only problem with this is that any purchases made using the BT address will not be authorised with the new gmail Apple ID.
You can create a new Apple ID using your GMail account here:
Then you can sync your photos across all devices.Any music or Apps purchased on the BT Apple ID will not be authorised and will not work on the devices that are configured using the new GMail Apple ID.
Once you have created the new Apple ID on that page, I can help you configure the iPad and the iPhone with the right settings.
Let me know how you would like to proceed please, thank you.