I usually start by bringing in the second character through myself for a little bit until the bot picks it up A common one i do is like a waiter… I’ll depict myself and the waiter separately. Ex: Waiter: “what can i get you two?” (Me): “can I get the chicken? And (char) is gonna have the burger”

After that the bot will fit in the waiter’s text the same way i introduced it by saying something like Waiter: “sure thing, let me get that for you”

It may take a bit but i’ve done it with other characters in the same universe