This article describes how to setup two switches in a virtual 3-way. It will allow you to control the same load in multiple locations.
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First, navigate to the association settings of the first switch. In the Z-Wave JS UI select the first switch you'd like to associate. Then under "Groups" press the "ADD" button. Then set the Node Endpoint to Root Endpoint. Set the Group to Group 3 and select the Target Switch you'd like to associate. Finally set the target endpoint to "No Endpoint". Repeat for Group 4.

Repeat the above swapping the target switch to be Switch A.

The end result will be:
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Switch A:

Group 3 -> Switch B
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Group 4 -> Switch B
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Switch B:
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Group 3 -> Switch A
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Group 4 -> Switch B

The last step is to change the Configuration parameter of one of the switches so that it mirrors its received commands to the other switch. We need to make sure that we only do this on one switch or else you will create a loop of z-wave commands that will cause problems on the network.
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Choose the first switch. Usually this will be the "master" with the load attached to it. When you send Z-Wave commands to the virtual 3-way it will, in-turn, control the other switch.

Go to "Node" then "Configuration v4"
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Set Parameter 59 to 3
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Go to "Node" then "Configuration v4"

Set Parameter 59 to 1

parameter059 : [
number: 59,
name: "Association Behavior",
description: "Choose when the switch sends commands to associated devices",
range: ["0":"Never", "1":"Local (default)", "2":"Z-Wave", "3":"Both"],
default: 1,
size: 1,
type: "enum",
value: null
],