/ms sendgroup GroupName [command] - Sends the command to all characters listed in a group. Groups can be defined in Ashita/Config/MultiSend.xml. See XML Structure file for example.
/ms followme on/off - Enables or disables followme. When followme is enabled, any characters with follow enabled will follow the player who last activated followme.
/ms debug on/off - When enabled, all received commands are printed to log and any character with followme updated will spam log with position updates. For debug purposes, obviously.
You may use [t] [me] or [p0] [p1] [p2] [p3] [p4] [p5] to replace the <> equivalents, if you wish to resolve them on local character. This will replace them with the appropriate server IDs, allowing the command to resolve on receiving character.
Example: Typing /ms send /ma "Fire IV" [t] will make all characters with multisend loaded cast Fire IV on the character who typed the command's target, rather than their own current target.