How is egg move inheritance determined in Gen IV?

Hi all, I’m having trouble with a breeding project and hoping for some help. Thanks in advance. I’m playing Pokemon Diamond and trying to breed a Misdreavus with the moves Nasty Plot and Ominous Wind inherited as egg moves from its father, a Spiritomb. His moveset was as follows, all learned from leveling up:

HypnosisDream EaterOminous WindNasty Plot

But I just bred a few Misdreavuses with the following moveset:

Growl (lv. 1 move)Psywave (lv. 1 move)Ominous Wind (egg move)Dream Eater (egg move I guess, butI didn’t even think this was possible?)

I wanted it to learn Nasty Plot as its second egg move, not Dream Eater. I made my Spiritomb forget Dream Eater so he couldn’t pass it down, but now I’ve hatched a baby Misdreavus whoonlyknows Growl, Psywave, and Ominous Wind. Nasty Plot isn’t showing up at all, even though her dad knows it and it should work as an egg move. What am I doing wrong? How do I get her to be hatched knowing Ominous Wind and Nasty Plot? Thanks for any help!

Pleaselog inorregisterto add a comment.

In Gen 4, Nasty Plot is only an egg move for Misdreavus in HG/SS, which is why that isn’t working in Diamond (source). Unfortunately, PokemonDB doesn’t properly address these edge cases.

Dream Eater is being inherited because in Gen 4 (and all games prior to Gen 6), the baby will inherit any TM or HM moves known by the father which the baby is also compatible with. It only matters that the move is a TM or HM in the game in question, not that the Pokemon actually learned it using a TM or HM.