Sheila Probst Siggard’s big, red barn on nearly 8 acres in Midway has been in her family for as long as she can remember. All that time, it has been a muse for artists across the Heber Valley. During the Midway Art Association’s annual plein air contest, painters flock to the public roads surrounding her property to set up easels. There seems to be at least one artistic depiction of its two silos and Park City pine logs for each of the four sea…