How to prevent launch shutdown on single remote connection failure? (required="true" not working)

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I have a launch set up that includes two separate other launch files which are run on other machines. Those launch files have nodes with attribute required="true" set however, the first node fails to start because of a failed ssh connection and the second is never attempted as the launch file exits on the first failure.

I suspect that the required="true" doesn't take effect as the remote ssh connection fails before hand, but the machine and include tags don't have a required="true" option.

Is there a way to prevent a remote machine launch failure from killing the entire launch?