TDC1000-Q1: Can i add an analog switch in between TX1 and RX2 to do signal path open and close control ?

Hello,

In mode 0, the device is already switching between TX1 and RX2.  

If you wanted to control the switching, you could do this externally, but you probably would want a switch with a lower Ron specification.  You can find low Ron switches below.

https://www.ti.com/product-category/switches-multiplexers/analog/products.html#1143=1%3A1%20SPST&3143typ=0.12%3B5&