If you would like to know how to connect the 760 expansion battery to the 767 power station, please refer to this article: 

How to connect the 760 Expansion Battery to the 767 Power Station? (anker.com)

Regarding the charging and discharging sequence between the 767 PowerStation and its expansion battery, please refer to this article: 

What is the charging and discharging sequence between the 767 PowerStation and its expansion battery? (anker.com)

If you have any other questions, please feel free to contact us for help.