Honoring stepmom in Sand Ceremony for wedding?

I am very close to my step-mom. My parents divorced when I was 9 and my step mom had just as much a hand, if not more, in raising me. It would upset her and hurt her feelings if she was not apart of the mom part in the sand ceremony. My bio mom will not be upset if my stepmom was involved as she knows how I feel about her. My question is, how do I include my stepmom? Do I have her bring in a 3rd sand color then my mom and fiances mom bring in the main 2?? please help!