Comment reply @ name with space

Question

Consider the following comment thread.

This will not work, the foos are all wrong --john doe
@john Yeah, the bars too --john smith

If I reply using @john it will notify "john smith" but not "john doe". How do I reply to "john doe"?

How do I reply to someone named "BA Baracus"? Will @BABaracus work?

What if the name is "B. A. Baracus"?

What if, in the same comment thread, someone else is named "BABaracus"?

Note: I have read Meta Stack Overflow question How do comment @replies work? and Display names with spaces in the first few characters cannot be used in @ responses.

Answer 1

To quote How do comment @replies work?,

Spaces are removed from the display names for matching purposes, so to match Peter Smith you may use @pet, @peter, @peters, or @petersmith. The last two are useful if Peter Jones is also participating.

To answer your second question, it is only possible to reply to the most recent commentor of two identical usernames.