Syntax to add multiple commands to a single command block

Unfortunately, the answer for the format is:

N/A

Currently there is no way to set two commands in one single command block (after using the powerful Google). I don't know why, but you just can't.

If you want to set up multiple commands, use redstone wire to link them up. That's the most simple way.

You cant write multiple commands in one command block but you can use one command to spawn more command blocks. If you mess around with the Riding datatag you can get fallingsand entities with commands in them to ride on top of each other. For example:

/summon Falling sand ~ ~2 ~ {Time:1,TileID:137,TileEntityData:{Command:/say hi},Riding:{id:FallingSand,Time:1,TileID:137,TileEntityData:{Command:/say hello}} 

Now if you want them to activate simultaneously you could do something like

/summon FallingSand ~ ~1 ~ {Block:redstone_block,Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"/fill ~ ~0 ~1 ~ ~-4 ~1 redstone_block"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~3 ~1 stone},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:setblock ~ ~4 ~ command_block 0 replace {Command:fill ~ ~2 ~ ~ ~-8 ~1 air}},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"/say Hello"},Time:1,Riding:{id:"FallingSand",Block:command_block,TileEntityData:{Command:"/say Hi"},Time:1,Riding:{id:"FallingSand",Block:stone,Time:1}}}}}}}

This is the only way to get multiple commands in one command block, if you know how FallingSand works this would make a lot more sense, hope this helps.

An easy format I have come up with to do this without any external program with the falling sand method is to start with this command

summon FallingSand ~ ~1 ~ {Time:1,Block:redstone_block,Riding:{id:FallingSand,Time:1,Block:command_block,TileEntityData:{Command:____},Riding:{}}}

and insert your first command into "{Command:____}", replacing the ____, and then copy this:

id:FallingSand,Time:1,Block:redstone_block,Riding:{id:FallingSand,Time:1,Block:command_block,TileEntityData:{Command:____},Riding:{}}

into the brackets at the rightmost "Riding{}" and enter the next command into the next "{Command:____}". Once you have entered in all your commands, you need to delete the last Riding{}, or the command won't run. Keep in mind that the commands will execute in the reverse order than what you input them in.

If you want to delete the extra block spawned or even the original command block itself as well, then start with this command

summon FallingSand ~ ~1 ~ {Time:1,Block:redstone_block,Riding:{id:FallingSand,Time:1,Block:command_block,TileEntityData:{Command:/fill ~ ~1 ~ ~ ~-? ~ air},Riding{}}

and replace the question mark at "~ ~-? ~" with 2 * the amount of commands you used and add to that 2 if you want to leave the original command block or 3 if you only want to run it once and then delete it.