To be more specific, here are some images:
1).
https://imgur.com/a/CfNlNnM
On this image A is in close combat with B. A and B facing each other and can hit each other. No questions.
2).
https://imgur.com/a/hPNEPgm
Here C is joined the fight and now at the rear to B. Can C hit A?
3).
https://imgur.com/a/GcwEAmy
And now D enters the close combat. Whom he can hit? Is he at front of all of the fighters?
What if even more characters are want to join the fight?