LTC6811-1 Vref1 vs Vref2

k07s said:

1. How many thermistors can be supplied through Vref1, if at all?

It's not advised to connect thermistors/any load to VREF1 under any circumstance.
From the Absolute maximum rating section in the datasheet, you can notice that the maximum current in/out through any pin is 10mA. So you should accordingly adjust the number of thermistors, not to reach the absolute maximum in current sourced from the pin at any temperature in the expected range.

k07s said:

2. Will this cause damage to the LTC6811-1 IC, if we continue to use the Vref1 as the supply voltage for the thermistor network?

No, until you don't exceed the absolute maximum ratings mentioned in the datasheet. But it's better not to use VREF1 as when any load is connected to VREF1, you can expect a drift on the VREF1 and there will be a significant rise in TME from what's mentioned in the spec.

k07s said:

3. Is this a significant enough of a problem that we should cut the track from Vref1 and put in a jumper to Vref2?

We better suggest you do so if possible. It won't be of a significant issue until you don't mind the drop in the accuracy of the conversion results. And please note that the error in conversion results might as well worsen in long run.

Thank You for your detailed answer, I would still like to get one thing cleared; As I understand using Vref1 instead of Vref2 would only be affecting the accuracy of the measurement and unless the current limit of the pin is exceeded there should not be any physical damage to the LTC6811?

k07s said:

As I understand using Vref1 instead of Vref2 would only be affecting the accuracy of the measurement and unless the current limit of the pin is exceeded there should not be any physical damage to the LTC6811?

Yes. In your case, you can expect no physical damage to the device unless you don't exceed the absolute maximum rating in the current sourced out of those pins.