AaronOfBarbaria
Adventurer
You're asking the wrong person - I'm not the one that was curious about doing it, just the one that covered what the rules say on the matter (a matter which I'd never even considered before seeing the post I was answering earlier).Why on Earth would you want to?
You are basically just listing the definition of a house-rule at this point - the DM may either go with what the book says (the official rule, which is that racially granted cantrips do not have any bearing at all over things which they do not mention such as other spells gained from other sources), or with something else (a house-rule).The 'house-rule' depends on how your DM rules...
The only time their can be two (or more) differing rulings for the same rule, and none of them be a "house-rule" is when the official rule is literally "whatever the DM decides."