I talked to a gentleman who said several years ago he was listening to Paul Franklin on steel with a band at the Preston hotel in Nashville. Barbara was in the audience and Paul had Barbara sit in with the band and play about four songs on steel.
The World's Most Famous Unknown Band From March 1990, Chet Atkins presents "The World's Most Famous Unknown Band" in a salute to Ralph Emery, and that band is: Glen Campbell, Jerry Reed, Steve Wariner, Roy Clark, Ray Stevens, Ricky Skaggs, Lee Greenwood, Steve Gatlin, Barbara Mandrell, and Irlene Mandrell.
And likely, if you had stopped her right there and said "what are you doing right there?" she would've clocked you with her bar and chased you out of the building.
Just spotted this YouTube clip of the Mandrell sisters...
At 1:20, Barbara plays a great C6 solo on “Oklahoma Hillsâ€, after Louise’s fine fiddle solo!
(Is that Mike Jones, Barbara's steel player for many years in the clip?)
Then at 3:03, Barbara and Louise play 6-string guitars in harmony on the opening solo of an uptempo version of “Ghost Ridersâ€!
Barbara is definitely just as her sisters are. I have noticed she plays fast instrumentals on the shows I have seen. I wonder if there is a video of her playing fills behind a singer.