DWDitty,
Sam Pirt's post gave me another idea. This summer there will be many folk festivals that provide instructional weeks, often including vocal techniques and HARMONY. There are two I am certain about. Commonground meets the week following July 4th (7/4-7/11) right here in my hometown, Westminster, Maryland, USA (30 miles northwest of Baltimore). Their web-site is www.commongroundonthehill.com. One class is called "Harmony Singing" led by HOT SOUP!, a trio of my buds Christina Muir, Sue Ribaudo, and Sue Trainor.
Then August 8 -15 is Vocal Week at Augusta Heritage Center (www.augustaheritage.com) at Davis and Elkins College in Elkins, West Virginia (northwest near the southern Maryland border). I have not personally been there, but I've heard many good things. Well HOT SOUP! is leading a weeklong harmony workshop there.
There are surely more, but these are two I know about.
Enjoy the songs!
Roger in Baltimore