Questions about mqtt in meshtastic – Support

I have 2 tbeam, 1 heltec v2, and 1 ttgo, right now I have a lora mesh with the 1 heltec, 1 ttgo and 1 tbeam, all of them are my nodes, then 1 tbeam is the gateway, ok, so, in one of the nodes i have enable the range test plugin, with that I can send automatic data, like seq 1, seq 2, etc…, and that data is sended to all the nodes + the gateway, the thing is, that i wanna know is there a way to send data from another mqtt server like mosquitto and receive the same json that i get in meshtastic mqtt server, if is yes, where i can find the code to modify that json? and is there a way to publish a message and see that message in my tbeam nodes?