Yes but as usual grasshopper you have surpassed the teacher. I'm not remoted, I'm actually at the office but about to leave and trust me you don't wanna know.
It's lonely at the top.

Keith office drama aside, the good news is it sounds like you already have everything in your cabinet that you'll need to make this work. Just send this over to your vendor and you should have no problems. If they need more information, the tech can create an account here and I'll be glad to walk him or her through it.
It sounds like your single line card has extra ports available so each fax machine will get an extension off that card.
Have your vendor program the extension to be a "House Phone" and when the fax machine goes off hook to dial out, program the House Phone field to automatically dial 8 for an outside line. If you have call waiting on your lines it will also need to be programmed with a 1170 or whatever the code is in your area to disable call waiting for that call.
The next thing you need to do is to go create two free Google Voice numbers. These will be your new fax numbers. If you don't know how to do this, just Google it. You're going to set your Google voice numbers to forward to
two of your four incoming phone lines. What I mean is that one GV will forward to one number, and the other GV will forward to another one of your incoming lines. The reason is that Google won't let you forward two GV numbers to the same phone number.
Once you have set up your two GV numbers and set them to forward,
this is key. Set your options in the GV control panel so that it does
not announce the call, and set GV to
transmit the number of the GV, not the number of the caller. So in other words, if I send you a fax, your caller ID would show the GV number on your screen, not my number. Don't worry, if you ever need to see the caller's CID you can just log into the GV box and it will be stored there for you.
Now tell your vendor to program your switch so that all four of your lines ring into a Call Routing Table. The CRT must be configured to route by incoming CID. Then program the table so that if the number from the first GV box rings in, it automatically routes to the extension for the office fax. If the number from the second GV box rings in, the CRT will route it to the warehouse fax extension. If any other number rings in, then it will ring to wherever you have them now, such as an automated attendant, reception desk, etc.
If your vendor needs more information, we'll be glad to help.