This is a great idea - memorial candleshttp://custompersonalizedcandles.com
We had a short prayer said at the beginning of the ceremony recognizing all the loved ones that weren't able to be there with us.If it's a parent or close family member then you can light a candle or reserve a seat and place a flower in it on the way up to the alter. Whatever you decide, don't make it a big thing because it will put a damper on the day.
There are many subtle ways to remember loved ones during a wedding ceremony. You do need to make sure that whatever you do, you make sure it will not catch any family members off guard and cause them any unexpected grief or sadness. Brides can wear jewelry that belonged to loved ones who have passed, or attach a locket or other heirloom to their bouquet. You can incorporate someone's favorite color or flower into your decor. You can play a favorite song during your ceremony or reception.