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I want to add a hidden Pre-Chat field
and when an Experience User launches Chat on an Experience site, I want to pre-populate a hidden Pre-Chat field with a Community User's associated Account on the form.
I then want to use Direct-To-Button routing (https://developer.salesforce.com/docs/atlas.en-us.snapins_web_dev.meta/snapins_web_dev/snapins_web_directtobutton_routing.htm) to send the User to the appropriate Agent, based on Account Team Membership.

How do I add and populate the hidden Pre-Chat field?