Well, you can just outright name your units, or assign variables/substitutes in there for them, but I find just leaving the name in makes debugging easier.
Man1
oymancopy
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Man1 sidechat "oh my, oh my, I broke a nail, what to do..."
~2
oymancopy sidechat "You sod! Start shelling the enemy! I'm pinned down!"
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There's a few different radio types (vehiclechat, globalchat, etc) but I usually use sidechat.
Hope it helped,
GRK