To answer your question, you can have more than one output to a block. You right click on the line coming out of the block and choose Insert assignment. It will add a branch and area for you to type another tag name. Like this:
Now for the real fun. Why, just because. I have created a simulation of your application from your description. Here's the thing in action with a program I wrote.
https://youtu.be/407T8KZ_09s
I also exported the relevant files so that you could play with it too. The file you need to import into your CoDeSys project is attached to this message as a zip file. You need to unzip it ant then import it as shown here:
https://youtu.be/QP431WuTVm4
Once you have done the import, Use the tags in the Global Variable file GVL in your PLC_PRG. Make sure you are in simulation mode (see video) and then go online and run the project. You can see if you are doing things right.
It would be no fun it I give you my program right away since you want to do this as a learning exercise. Start slow. Just run it with the one network shown in this post and you should see the light come on and M2 come on. The tank won't fill because you haven't turned on a valve yet. Once you get that one network working, then try to open the first valve and start filling.