Questions about phrases and phrasegroups

[Whissi]

Hello,

I am writing a modification with an own file in admincp.
Should I create an own phrasegroup?
When I don't create an own phrasegroup, where should I put my phrases into?How does the $phrasegroups array work? I thought that I can put my phrases into any phrasegroup and when I want to use them, I only need to put that groupname into the phrasegroups array, but it seems that I am wrong, because I cannot use phrases, when they aren't in "cphome" or "global".

Thanks.