Have you tried adding event to the prefab? If it doesn't work you can attach event to the empty object in the scenery and pretend it's prefab that is speaking.
Beside what @JRM said, you can also set up an actor to use Found Objects, Global Objects and Selected Data - so if you store your spawned prefab in one of those, you can use it as an actor and thus use it as a speaker in a dialogue :)
Generally, dialogues are limited to use actors mainly for the dialogue related information you can set up in actors, e.g. name and portraits.
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That works actually. Often time I will spawn a prefab and add a combatant to them for all of that info, in a cut scene. So an actor is the easiest to work with.
Generally, dialogues are limited to use actors mainly for the dialogue related information you can set up in actors, e.g. name and portraits.
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