Wasn't Wiglaf the son of Beornwulf, King of Mercia?
https://ancestors.familysearch.org/en/GKYF-585/beornwulf%2C-king-of...
This link, from the Church of the Latter Day Saints suggests the Beornwulf was married to Aelfthryth of Kent, fl 725, daughter of King Eadric of Kent.
https://gw.geneanet.org/tiaugn?n=of+kent&oc=&p=aelfthryth
Is there any validity to this?