Making Current To Flow In One Direction
If you are connecting the signals to a analog digital converter, the solution is to use a multiplexer, for example 4051 to switch safely, with minimal influence on other channels.
Of course, using a multiplexer, slightly increases the complexity of your circuit. The control circuit is not described in your question.
Anyway, R1, R2 and R3 resistances should be on the other side of switches.