It sounds like you think Sonja may still be living, and so you may not want to post too much detailed information about her. However, anything you feel comfortable posting about why you think she has connections to
Dallas County, i.e. we attended elementary school together at Interstate-35 school in
Adel in the 60's, for example, is going to help. Is
Hughs a married name? You might try one of the people finder services, like
www.ussearch.com -- they offer a lot of stuff for $30-$60 if you're that motivated <grin> but their free "preliminatry" search is nice because it gives ages and you can get results by maiden name, so it can help pinpoint the possible whereabouts of someone.
Good luck in your search.