CAN YOU CHARGE A DUAL BATTERY CONCURRENTLY FROM SOLAR AND ALTERNATOR ??

Hi
The short quick answer is YES
Depending on relative setting one or the other will shiut down as the battery approaches full charge
Up to that point both will contibute to the charge
Simply connect your panel via the panel reg to the 200ah battery

You may even @ times find the solar is topping up the main battery as well as the aux if the alternator reg has cut back

"Is it possible to charge from both the alternator and the solar panel at the same time.... "
If both 'regulators' (alternator reg and solar reg) are working correctly it is not even worth a second thought, they will regulate independently.

"should they be run ie, when motor is running (alternator) "
That will depend on what type of solar regular you are using?

"when parked (solar)
This assumes the motor is not running as your "parked" so the alternator is not charging the 200ah battery, only the solar panel will be.

"can you obtain a switch or should I manually unplug and plug "
You don't need to do anything, if the regulator is suitable, as it will correctly 'regulate' the Amps going to the 200ah battery.

Maîneÿ . . .