That can be done using nested mode if the minifig isn't a submodel itself.
Open model C
put it in nesting mode (N, while nothing is selected).
Cut the minifig (rember it's pos).
Then paste it again back to the same position.
If it is a submodel you need to be abit more tricky:
Open model A, select the minifig.
Add a brick to the scene (so it has the sameorientation as the minifig).
Open model C
Enter nested mode
Select the tmp brick.
Locate the minifig in the models overview and drag it in to the C model.
Hope that helps.
Open model C
put it in nesting mode (N, while nothing is selected).
Cut the minifig (rember it's pos).
Then paste it again back to the same position.
If it is a submodel you need to be abit more tricky:
Open model A, select the minifig.
Add a brick to the scene (so it has the sameorientation as the minifig).
Open model C
Enter nested mode
Select the tmp brick.
Locate the minifig in the models overview and drag it in to the C model.
Hope that helps.