The first idea is to add the short mother of the bride dress with a matching hat. In the past, a delicate hat could be considered as a symbol of elegance and grace. Therefore, a matching hat will add some formal and noble touches for a short mother of the bride dress to some extent.
Besides of hat, matching jacket or bolero can also make a short mother of the bride dress look more formal. Considering the cool weather of the autumn, you may also collocate your short mother of the bride dress with a matching long coat. Such a collocation must ensure you a elegant and formal appearance.
Of cause, some other accessories are also helpful to make for a formal look for a short mother of the bride dress. For example, a formal make-up and hairstyle will probably add some formalities. Elegant jewels, handbags or clutches, heels, and so on, can also be taken into consideration.