The scenario: Lots of MOGs keep their distance in an effort to avoid crowding the happy couple. Unfortunately, this tactic can actually make it appear like you don't care at all, even when that couldn't be further from the truth. While some brides will embrace this hands-off approach to wedding planning, others will be hurt by it.
The solution: Make a point to send your DIL the occasional e-mail checking up on the wedding planning process and offering your assistance as needed. When she does ask for something, like your guest list or your opinion on a possible venue, be sure to return the information to her as soon as humanly possible.
Above all else, don't hesitate to tell your DIL how much you look forward to having her as a part of the family. It can be pretty daunting to come into an established family as the newbie, so it never hurts for her to know that your son isn't the only one who wants her around.