Yes they do but the same computers(part #) as the one removing.You must not have a clue how the programming of vehicles computers is actually done.Did a lot of it when I was working at a dealership.If using a new or even used they must re-print the VIN in and then they can only program options for that VIN,they can't just put in programs at will.
Sorry to burst your bubble but I have worked at dealers and I know how programming works.
If a vehicle has a certain set of options available to it as long as you have the correct modules, controls, etc... it can be flashed to let them work. I am not saying to do it just that it is possible.
Lets use fog lights as an example. If your vehicle doesn't have them, but they are an option on a different trim level or something like that( available on your vehicle type is the point ), you can install them and then have the flash done to activate them. It may require a different control module that has the programming for fog's but it can be done( have to do that on my Brother's new Super Duty - needs the fog's and a BCM for it to work factory ). I added the factory fog lights and controls to a Chevy Equinox as there was no GM Accessories kit for it. I had to add a BCM as my Equinox didn't come with fog's and the BCM in my vehicle didn't have the fog light option. Got a BCM that allowed fog's and the dealer did the flash for me and everything worked. The same can be said for other features. Seen it and done it. The key is what you want to do has to be something available for that vehicle. You can't add things never available to the vehicle. The OP wants to add 4WD. The Patriot comes in 4WD so if he added everything required it is "possible" the dealer could do the required flashes/activations to make it all work.
Now, it is possible that on a Patriot the 4WD stuff couldn't be added. Some vehicles allow for things that others don't. Like the way the Patriot is so limited for tire size changes with a flash. Other Chrysler vehicles can have a flash done using the tire dimensions and rev rate of the tire. Some vehicles seem more modifiable than others. It is also a very real possibility the dealer wouldn't be willing to do it. I am not saying anything other than I believe it may be possible to do it.
To say it can't be done as a blanket statement is just flat out wrong because it implies nothing an be done on any vehicle. Again, I am not advocating this be done by the OP. I have said repeatedly I would not do it. I do not believe it is 100% certain though that it can not be done. I would wager with enough money and time it could be.
I will say that your claims nothing can be done that isn't tied to the VIN( i.e. stock configuration )is just foolish though. You seem to be the one who doesn't know as much as you think about the programming.