"That is not our mother!"
Translation:Das ist nicht unsere Mutter!
From what my humble knowledge can tell, but I would rather for someone to confirm, is that in german the nicht negates can negate adjectives, verbs (working just as an adverb), or it can negate the whole sentence. So your supposition would be technically correct, I guess so, though sometimes negating the verb when for them it is technically correct to negate the verb can sound a bit unnatural because tit wouldn't "be the way". I need to read more about negating sentences :v