1 join 1 is when dude1 joins grpNull.
Do you have a group called betagrp with people in it? You need to give the group a name, in this case betagrp.
If you do the second instruction will cause them to join dude1 with him as the leader of the group.
Really this second line is the same as dmakatra's method. Where his and my method differ is really only in the first instruction. Telling dude1 to join a group will not make him the leader of that group, but will get him out of his current group. Telling him to join grpNull gets him out of the current group, you then get the other guys to join him (and so make him the leader), either by using dmakatra's method of naming each individual unit, or my method of using a group name. As I said in principle the second instructions are equivelent in both methods