Yes, because what you're doing is you're taking data and replacing it.
I recommend that you extract a CH#.PAC with the PACeXtractor and once you've located something, open it with hex, copy a bunch of lines, look for them in the original CH#.PAC, then copy the PAC block and save this thing as a separate file. This way you would have the smaller PACs, which are otherwise unattainable, in a separate small file which you can more easily edit and have more than one copy of.
I used the FRhead hex editor, because it is free and has so many helpful features which make the load of work you might need to do so much lighter.
God luck.
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