The German immigrants to Pennsylvania in the Eighteenth Century seem to have been generally able to sign their names, which they did at least once on arrival in Philadelphia. Such people as might have been our ancestor spelled their nameWeyandt, Weÿandt, Weygandt, Weylandt, Weynandt. One who couldn't sign his name found it transcribed as Viant. This shows how our name developed.
The record keepers in Colonial Pennsylvania were English speaking and tended to write down the German names as they heard them. By the third generation many families had lost contact with their origins, moving ever west to new land, and in many cases had little or no schooling. As our family name was passed on aurally it was modified. If there was a middle consonant it disappeared early and we have not been able to make such a connection. For most branches of our family the final consonant 't' disappeared, leaving some phonetic form of Wyan. The families that stayed in Mifflin County became Wian.
It sometimes happened that our family moved to an area where there was an unrelated family already established. In Bedford County they were assimilated into the Weyandt clan, becoming Wyant - the only branch to keep the t. Some later actually changed their name to Weyandt.
In Clarion County they became Wyon.
In Ohio they became Wyan and Wion.
In Centre County my own branch settled on Wion. My great-grandfather, Daniel put Wian on his mother's tombstone - his son put Wion on Daniel's! The children in another Wion branch were told by their school teacher that they were spelling their name incorrectly - some kept Wion, some changed to Wian.
Ironically, most of the Wions in the U.S. are (as yet) totally unrelated, descending from an early settler in Muskingham County, Ohio, who became known there as Frederick Peter Wion.