CraftyGames People, I think you made a slight mistake w/ the properties of Feruchemical copper. It says that when you store a memory in a coppermind, it can only return while tapping and can never be altered in any way. The first of these points implies that the memory goes away again when you release copper. What I thought was that tapped memories were treated exactly like regular memories, (i.e. they decayed normally and remained when you released copper) but that Keepers usually stored their memories again as soon as they were done with them to slow decay.
Sazed mentions in the early WoA that copper memories grow fuzzy if you tap them too often, as the brief instances of decay add up.
Also, I thought that if you learned something new relevant to a particular memory, you could simply add that to what you stored.
Please work out whether I'm misunderstanding you, you misstated, or I'm just wrong on how copper works.
My apologies if this is rudely phrased, and thank you for a wonderful game!