Your friend needs to join the server at least once for you to build on his bricks.
Ah, I wasn't aware there was a console command that did that.Do you happen to know it? It would benefit Emmanrocks in this situation, and it'd be interesting to know.
for(%i=brickgroup_1337.getcount();%i>=0;%i--) { %brick = brickgroup_1337.getobject(%i); brickgroup_666.add(%brick); %brick.stackbl_id = %bl_id; %brick.client= %cl; }