Auto selecting DCDC charger input

[Banga315]

Hi guys,
I have a strange situation where I am designing a system for my mother's motorhome. I want it so she doesn't have to change any wiring while on the road.
I have a 12v LiFePO4 battery bank in parallel, and will connect it to a DCDC charger, which will connect to the alternator for charging while she is driving.
The problem I am having is that I want to also connect an AC to DC power supply (which is withing the V and A of the solar input of the DCDC Charger - 25v/25A/625w), as well as her 400w of solar on the roof. Now, I don't want to just connect these up in parallel and connect to the solar input and fry the solar panel when she plugs in at caravan parks (or wherever). I was hoping there would be something like a SSR or auto switch that when there is voltage in the line coming from the AC-DC power supply, it breaks the circuit of the solar.
I was hoping that the DCDC charger can pick up the 625w from the power supply and put that into a form that can then charge the battery, then when she disconnects from AC the solar takes back over.
I hope this makes sense. Please feel free to throw any questions for info that I may have missed. Here is what we already have and don't have:

I Have:

• LiFePO4 battery bank
• 25V 25A AC-DC Power Supply (this is not a "charger" but a fixed voltage and current power supply
• Renogy 50A DCC50S

I DON'T yet have:
* Any switches/relays needed to isolate the circuits....

Thanks in advance,
Stu