How do I save my changes to Simcity_1.dat?

[Moonraker0 192]

I just edited about a hundred OccupantGroups records from Simcity_1.dat in Reader.  I tried this before, saving over Simcity_1.dat, but that messed up all of the PNG files in the .dat.  Now I realize that it's probably a bad idea to save over Simcity_1.dat (I had a backup from before), but I don't know how to make my modifications a separate file.  I read here that there is a record modification button that one should press before modifying records so that they can be put into a separate .dat file, but I didn't know about this at the time, so I didn't press it.  I don't even see that button in the new Reader; was it taken out in the new version?  I tried using Save As to save a completely new file from Simcity_1.dat, but I think that this new file has all of the records of Simcity_1.dat, not just the ones I changed.  So, how do I save my changed records?  Or do I have to hand-edit all of those buildings for a third time?

Nevermind.  I figured out that I can just use the "Add to patch" function after selecting the modified files and then save a DAT of them.

[local_authority01 3]

It is MUCH, MUCH better to make .dat patches then to overwrite simcity_1.dat. These patches can always be changed and edited and removed without screwing up the game. If you change the simcity_1.dat files you may screw up the game and have to re-install it to get the original simcity_1.dat file.

It is also important to make a backup copy of simcity_1.dat if you plan to be editing a lot of things. Save it in a folder outside of the game. This is a very important file and should not be overwritten.