This article explains how we can renumber a member in a VC

Customer connected two standalone devices through a VC-Port (unintentionally) caused both standalone device to form VC with one member as fpc0 and another as fpc1.

When the cable was removed one member still was using fpc0 and another member was in fpc1.

To recover from this condition we renumbered memer 1 to member 0. Post that the device is recovered completely.

To renumber the member we can use below link

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/command/request-virtual-chassis-renumber.html