How to add more than one machine to the trusted hosts list using winrm

Question

To run powershell commands on a machine from a remote machine we have to add the remote machine to the trusted hosts list of the host machine.

I am adding machine A

Answer 1

The suggested answer by Loïc MICHEL blindly writes a new value to the TrustedHosts entry.
I believe, a better way would be to first query TrustedHosts.
As Jeffery Hicks posted in 2010, first query the TrustedHosts entry:

PS C:\> $current=(get-item WSMan:\localhost\Client\TrustedHosts).value
PS C:\> $current+=",testdsk23,alpha123"
PS C:\> set-item WSMan:\localhost\Client\TrustedHosts –value $current