First, you have to extract the zone file from the patch fastfile. Then you open two windows in your hex editor, one for the modified zone and the other one for a zone from a "clean" patch (or one without those edits). Now I were you I would just search "{UU}'s Invitation" as a text string. Go to the same address on the clean zone, then copy and OVERWRITE to the modified zone file. You can also find guides on here for all the offsets.
You can use
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But if you have no idea what I'm talking about, it would probably best if you had someone else do it for you.