Alyson

Alyson is a spelling of Alison, which developed as a medieval French familiar form of Alice. Alice ultimately belongs to a Germanic family of names associated with nobility. Despite the son ending, this history is different from English surnames that literally describe someone as the son of another person.

The y makes Alyson distinct from Alison and Allison without creating a different underlying meaning. Ali and Allie remain possible short forms whichever full spelling is chosen. For a family honoring an Alice or Alison, Alyson can preserve the relationship while changing the written form. The spelling choice is more significant here than looking for a separate ancient origin for each version.