Heiress sits next to 3 phonetic neighbors — Paris, Harriet, and Eris are the closest matches by sound. Most share Heiress's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"one who inherits, female heir"
"flowing from God"
"God is gracious"
"gift (via Kyra/Kyros)"
"lake (lynn element)"
"victorious woman"
"modern invented name with English meadow roots"
"work and power"
"salty, of the sea"
"boundary, limit"
"gift of God"
"modern creative coinage, possibly from Greek xanthos (golden) or Th..."
"sea, ocean"
"clearing with box trees"
"who is like God? (rhetorical, implying no one)"
"sunny place, facing the sun"
"Mary + Lynn (lake)"
"God is my strength, my God is high"
"lake (lynne element)"
"mercy, compassion, grace"
"well-born, noble"
Similar sound: These names share phonetic patterns with Heiress — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old French/Latin origins, giving them the same cultural heritage as Heiress.
Rhythm: Heiress is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.