Building a Ghost-Follower-NPC Issues

[Gorgopis]

Please advise:

In the CK, we built a ghost-follower, (with an existing follower-voice-type), (added a correct keyword), and added the ghost to all follower factions.  Her .esp is currently a "plug in" under an existing parent mod, not skyrim, not update and not the DLC.

In game, she does appear as a ghost, but she does not offer the expected follower dialogue.  (A couple of online tutorials show that it seems possible to accomplish, as the online models do offer the dialogue.)

Without a ghost script added, she does not show up as a ghost. And we forgot to test her dialogue.  But with the ghost script, she appears as a ghost, but she does not offer the dialogue. 

We think that might have to do with the default ghost script, which includes "ash on death", which we would not prefer, as we have marked her essential. 

We also wonder about the cell we placed her in, in Helgen Cave prior to the Chargen Exit, for those familiar with that cell point on the map.  We have successfully placed dead NPC's in Helgen Cave, but not a live one, yet.

Perhaps some game cells do not allow placement of new followers with "follower dialogue"?   We have not seen nor heard of that, but maybe?  We would like to understand the CK "logic" for our disappointing result, so far.   

We are wondering if we might need to modify and apply the Katria Ghost script?  We would prefer our Ghost-NPC to appear in both .5 alpha and "fleshed" forms during gameplay, depending on game events, which is more interesting than the "white-fuzzy ghost-look."  

We would be grateful for any experience or ideas.  (2 of us are working on this mod.)

[Gorgopis]

Oh, we just noticed that this creation kit forum says "Skyrim," so we should specify that our intended mod is for Skyrim se. We have built successful mods for both iterations of the game.

[scorrp10]

You did not need a script.    Just add 'GhostAbility' as one of her spells.

What the default ghost script  does:
OnLoad:
     Adds GhostAbility spell  (which makes her look like a ghost)
     Adds GhostResistsAbility spell (immune to poison and frost - if you want that for her)

OnHit
    Flickers the ghost for 3 seconds when hit by a weapon.   Again, optional.

OnDeath
    Turns them into a n ash pile.

I took one of follower mods I had installed.   (Inuel by LamaKreis)   She is already part of PotentialFollowerFaction, has Friend relationship with Player, and has a Sandbox AI package
In Traits, checked 'IsGhost' and 'Doesn't Bleed'
Added ActorTypeGhost keyword.
Added GhostAbility spell in the spell list.

And she was a ghost and had proper follower dialogue.