Need help making a Tiga child theme backwards compatible

I have several people who use a child theme of Tiga for their sites. I tested the recent Tiga major update on a dev server, and it broke my child theme. The main issues were the social buttons, widget positions, and custom backgrounds. I have reworked the *new* child theme (compatible with Tiga 1.0) so that it recognizes the old widget positions. However, I need it to be able to recognize what the user had set as a background through the old Tiga theme, and NOT have to go through each site individually and manually change how the background is called in.

What can I add to the new child theme to get it to recognize the OLD way a custom background was chosen?

Thanks in advance!