They won't be adding /t claim to the nether according to that Trell I card, so thus this suggestion. They also don't need to correlate it to the overworld as there won't be many people claiming large chunks of the nether (still get included in town taxes)
Even just allowing it in nether would be possible since the plot claiming part of the towny plugin corresponds with chunks, and the nether has chunks (even if it's smaller than the overworld in block by block; chunks are still 16 by 16)
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