Anker 760 Portable Power Station Expansion Charger

What about to introduce an external charger to solar recharge Anker 760 Portable Power Station Expansion Battery without having to connect to 767 master unit?
I’d like to have 767 connected to my fixed loads and bring out only 760 expansion battery to solar charge during the day and connect to 767 only in the evening to use the power without to disconnect loads.
Something like Bluetti DC Charging Enhancer (D050S) with b230 expansion battery.
Regards