Merion sits next to 4 phonetic neighbors — Marion, Merrion, and Meirion are the closest matches by sound. Most share Merion's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"From Meirionnydd; of the Welsh coastal region"
"kingly"
"prudent, wise, showing good judgment"
"Christ-carrier"
"the day (personified deity)"
"powerful counsel"
"auspicious, divine blessing"
"lion-hearted"
"yellow-haired, golden"
"from the hill settlement, dweller by the downs"
Similar sound: These names share phonetic patterns with Merion — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh origins, giving them the same cultural heritage as Merion.
Rhythm: Merion is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.