Undead Master and Necrocraft Shenanigans

[MongoLikeCandy]

How does the Undead Master feat interact with creating a Necrocraft monster? Does it increase the HD limit by 4? Necrocraft requires Make Whole. Do I need to increase the caster level for that as well to be able to boost Necrocrafting? Desecration work as well?

Or, is Necrocraft completely separate and simply has a hard limit of HD cannot exceed your caster level?

[boring7]

DM's discretion. Most of the time they'll let the feat count for the construction though, it is certainly "in the spirit" of the rules.