Are you asking them for their preference via a registration question or are they selecting a session and then you're reallocating them?
Because if it's the first one, my initial thought would be doing it via a session email instead and using the Invitee Answers data tag for their preference and the session name tag for their allocated session.
So for example "We've received your request to join [Invitee Answers data tag]. We've allocated you to [associated session name]."
If they're selecting the sessions themselves and you're reallocating them, the only way I can think to do it is create a custom field with the session names, and record their preferenced session as a value in the custom field on their contact record, then use that data tag.
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Carl Jackson
Digital Producer
University of MelbourneAustralia
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