OK, J1 is the same connector I measured the resistance on earlier. Counting from the left Terminals 1 and 2 on the connector have individual white/yellow wires that join about two inches out of the connector and dissapear as a single white/yellow wire into the fridge.
In other words I don't believe I see the 'jumpering' I'm looking for, or should I be snipping one of those wires?
From what Poobah is describing this is the jumper wire. I only show a single FF thermistor for your model so they must have used the same one for input to terminal 1 & 2. Since your resistance was the exact same I suspect you are on track. Cut the wire leading to J1 - 1 leaving yourself some room if you need to splice it back.
From what I found the original board number was WR55x10174 which no crosses to the WR55X10552.
BTW sorry I wasn't more specific on how & where to test the thermistors.
Here you have it. Remove the molex plug from the board to test. Pin 5 is common to all the sensors so put one lead there and leave it. Then check from 1-5, 2-5, 3-5,4-5 - If there is not a wire on 1 or 2 don't worry, record the readings and take a look at this to see where your numbers fall.