When I winterize I only put the pink stuff through my pump and blow down the rest with air.
To accomplish this I added a 3 way valve to the pump suction and another to the discharge.
If I want to add water to the tank from some sort of reservoir (gerry jug, bladder tank etc.) I would run a suction hose from the pump suction 3 way, to that and attach a discharge hose that is plumbed into the tank suction, to the pump discharge 3 way. I've placed a remote switch at the pump to control it from there if the main pump switch is on.
Water will be sucked from the reservoir & discharged into the RV storage tank.
It won't be fast but it will git'er done!