Re: DS9, Worf and Continuity.
As far as Alexander's first appearance goes, when K'Ehleyr first appeared, it seemed Worf had already had a previous relationship with her, so, I assumed she already had Alexander from that previous relationship, and just didn't bother telling Worf about him? So, I never questioned him being about6 on his first appearance.
In New Ground Alexander tells his teacher the stardate he was born on (43205) which places his birth in TNG's third season. Therefore he was conceived during The Emissary.
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