This from a pro-JW website:
Non JW Bride-to-be:
I recently learned that my JW Grandmother and Dad's JW family will not be attending the wedding portion of my wedding because it is a church of another faith. I have to admit that I am very very hurt by this. My Grandmother is the only Grandmother I have ever known and means so much to me. The fact that she will not see me walk down the isle and say my vows, the whole affect of the bridesmaids, flowers etc. really breaks my heart. She will be at the reception to see me but I will not look the same as I will in the church etc. In my religion I am permitted to go to other churches etc. I just don't participate in the things I don't understand/beleive and do not take part in their communion etc.JW # 1:
Love works both ways. You don't understand why they won't attend your wedding in a church, and they may not understand why you don't arrange to have your wedding in another place so that they can attend.I'm sure they would LOVE to see you be married. Must it be in a church though? You could make adjustments if you really wanted them to be at your wedding. You could simply arrange to have it at a more neutral location. It is your choice of course, but for me, my family being there would be more important than where I had it.
JW # 2:
As has been stated, there are reasons that a witness could with good conscience attend a wedding in an other religious building. I have done so since I have been a witness. But, if one of my grandchildren join another religion and get married in a religious building, I will not be at their weddings. The reason? I love them so and I have done all I can over the years to show them why being a witness of Jehovah is so important. That the bible tells us to get out of Babylon the Great. My love for them would not allow me to attend a religious ceremony of any sort to do with them. I will do what I can for them apart from attending the religious building. I will continue to tell them about the good things God has in store, and I mean by them, my grandchild and spouse, if I am allowed. Once they are married, I will have deep respect for them both. If they have children, and have them baptized in another relgion, I will not be there. I am telling you my feelings on the matter, but these feelings may be shared by your grandmother.
Please, go on loving her and respect how hard it is for us as loving grandparents not to be able to share your every joy.JW # 3:
The love that you process for you family should cover their desired to not be part of your Catholic Wedding. They are not doing it to hurt you, or because they don't care about you, they are doing it because they love Jehovah more and they feel they would offend him if they would go inside the Church. Don't focused in what they are not going to do, instead happily share in what they are willing to do.
What a witness to the Only True religion, eh?