[Dx4win] How to "unmark" NIL qsos?

[Larry Alkoff]

I sometimes get QSLs from a station or manager
and one or more QSOs are marked Not in Log (NIL).

Because DX4Win doesn't know these QSOs are effectively dead
they don't show up in spots.

I don't want to delete these QSOs as my practice is to never delete data.

How can I mark such QSOs so spots show up and I get another chance?
Mark them "invalid"?

Larry Alkoff N2LA