OK,
1] Create a logic called "server" on the map. Well, now you have integrated in the map that there is a server side and a client side of the game. First things first
2] Have a script on server side running that coordinates the Napalm strike (as i do not see your precise application this bit is speculation). This can also be a trigger on the map that is activated -> triggers are always executed on all clients without extra steps. To execute a scripts on server only (from the start of the game) put in init.sqs:
?(local server): [] exec "Napalm_server.sqs"
3] The server cannot start a script by its own power in the clients. Instead we have all clients run a script from the beginning of the game that detects the location and time of a Napalm strike. Put in init.sqs:
?!(local server): [] exec "Napalm_client.sqs"
4] Put in init.sqs a definition of the strike-coordinates as a global variable that are non-functional. Might be like this:
Coordinates = [0,0] <- Note the lack of underscore before"coordibates" making it a global variable
5] Have the server side script changing the strike coordinates to where you want to have it (again, this bit is speculation as i do not see your precise application). As an important step this scripts refreshes the global variable "coordinates" using the "publicVariable" command. This way the server tells ALL clients something is happening (like broadcasting). It will be like this:
?(Napalmstrike == true bla bla bla*): coordinates = [2705, 5658]; PublicVariable "coordinates"
*Put your own conditions here, depends on other scripts and map design
6] Have all client side scripts wait for the "coodinates" global variable to be different from [0,0]. If altered (by server of course) then they will execute the Strike at client-side. Like this:
#top
@!coordinates == [0,0]
_xcoordinate = coordinates select 0
_ycoordinate = coordinates select 1
<here comes the napalm script using the _x and _y positional info>
coordinates = [0,0]
goto "top"
These lines await signal of server, executes the strike at the position as defined by server and, finally, resets the coordinates to be ready for next strike. Note that the cllients do not need to "broadcast" the coordinates back to server and other clients, so the "PublicVariable" command is not applied here.
Good luck,