How do you write 2 or more characters saying almost the same thing in unison?

Question

When 2 or more characters speak in unison you can generally do something like this> "awwwww, she's so cute!" the girls said in unison in near perfect harmonybut what about when the line is only slightly different> Person 1: but i'm not...Person 2: but she's not...How would this be written?

Answer 1

Hello,

You can use the long dash and put both speakers on the same line.

"And is this your girlfriend?" Mom asked. 

"No, I'm not — " "She's not — " we both protested immediately.

Hope this helps.