Tidy, I think you might need to reply just to close it off once and for all; otherwise I can see you being harangued not just via email from Gluesis but maybe by phone/text by GZ and others. The closer the date gets, the more bridezilla she will become.
I also think that in GlueFamilyRobinson's heads, the fact you aren't going to the wedding also means you are unencumbered with tasks such as sorting out your outfit, hair etc to attend as a guest, and this then means you have more time on your hands than the actual invitees (and the wedding party, which if the STD and venue fiascos are anything to go by then there are certainly a lot more tasks to get through before the big day).
I think your reply needs to be:
Dear Gluesis, thanks for your reply and just to confirm, I am not available to assist with wedding preparations. Wishing you all the best for the big day, Tidy