It Seems You want to broadcast a messsage from one client to all client on openfire sevrer there are one plugin available with name Broadcast which will help you to do this.
There are many option available in that plugin like if you want to send only online user,offline user or just for some users
Hope i got you correctly if i am wrong then help me to understand your point.
Broadcast plugin only helps if a client has an option to send a message by manually entering recipients address. Say Spark doesn't have such option, so you can't use it with Spark. On the other hand, many clients already have mass message options (Spark calls it "Broadcast message" though it is not using Openfire's Broadcast plugin).