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If you need to introduce a new character to move the story forward, do it. Picking the flavor of POV is secondary, you can be either objective or subjective, the choice is yours only, and only the ...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/25154 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
If you need to introduce a new character to move the story forward, do it. Picking the flavor of POV is secondary, you can be either objective or subjective, the choice is yours only, and only the time and your alpha readers will tell, if you were right. The only advice is—do not abandon that character, when his or her task of progressing the story is done. Make sure they either stay in the picture or exit meaningfully. My preferred method would be killing them, of course, but it's just me. :-)