Dallin sits next to 3 phonetic neighbors — Dillon, Dylan, and Dalton are the closest matches by sound. Most share Dallin's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from the valley"
"lion man (from Leander)"
"foot soldier"
"broad valley, wide hill"
"olive tree man"
"zero, emptiness, infinite possibility"
"chief, royal descendant"
"supplanter (via Jacob/Kobe etymology)"
"of the valley"
"moon, moonlight"
"island meadow"
"son of Ken, son of the bold"
"of good appearance and strong physique"
"noble, powerful"
"deer meadow"
"apparent, visible"
"roses"
"settlement of Holston, holly stone homestead"
"rocky settlement"
"island meadow"
Similar sound: These names share phonetic patterns with Dallin — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old English origins, giving them the same cultural heritage as Dallin.
Rhythm: Dallin is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.