Have filled the grid. Found 3 names to replace.
No idea what birthname including an abbreviation to use.
A 5 letter name can be replaced with Niall to make real words.
But no such person comes to mind.
Hello Hankir. I'm in the same postion as you. Have the three names and the date, but cannot find a person, smilarly, but differently, connected with the date.
The preamble says 'after this replacement, all crossing entries will still be real words and proper nouns'. Note the 'crossing entries'! There's a similar person connected with the date, but the connection itself is not exactly the same.
Aye, i know what the 3 did, perhaps it's someone doing something at the other end of chronology, but his name doesn't fit JCC. Thanks for your kindness Neveracrossword! Loving the challenge. Now have a glass of wine which may loosen my thinking a bit!