Highlight Parent Menu Item while in Attachment Page

Hello Sakin, I followed instructions here: http://bibiano.io/highlight-parent-page/ and it works. However, many of the "sub pages" at on our website are attachment pages. For example, the images at http://www.sonomalavender.com/lavender-collection/stuffed-animals/ link to attachment pages. Is there a way to highlight the "parent" menu item (Lavender) when viewing these attachment pages? Thanks.