connecting two input channels to negative ADC-Input ADUCM360

Hi,

i am doing some ratiometric resistance measurements with the ADUCM360. Therefore I 'm using the excitation current source and both ADC's of the Chip. 

To avoid errors due to thermoelectric effects, I want to rotate the current source. Therefore I would have to switch the GND connections of my voltage Divider. 

My question is if there is a way to connect two input channels of the MUX, like ADC0 and ADC1 to the negative input of the ADC?