Sharing a single ground wire across multiple RTDs
Given the current thru each divider is 2.5/200 = 12.5 milliamps, if the Ground wire on the connector is 10 milliOhms resistance, the error change for each added RTD will be 0.01 ohms * 0.0125 amps = 125 microVolts ---- per added divider.

Examine your error budget and decide what is permitted.