If version of software is BC 11 or less then:
Command is
GPGMI :GRP=XX, DIR=YYY. [,LIM=] ;.
Parameter LIM is optional
If software is BC 12 or higher then
1. create group by command
GPGRI :GRP=XX, LIM=Z;
2. Add the member to a group by command
GPGMI :GRP=XX, DIR=YYY
XX is a group number ( I use number of room )
YYY is a dir ( extension number) You can use character & or &&
Z is a LIM number
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If anything can go wrong, it will.
(Murphy's Law)