Basic Ediquette

I would like to know if it is proper to invite guests to your Bridal Shower then exclude them from the actual wedding? My daughters (ages 24 and 20) have always been excuded from family weddings. When I questioned my Aunts and Uncles years back why my daughters were not being included since they were the same age as most of my cousins. I was told because they were viewed as "Second Cousins" and that they needed to draw the line on the invitation list some where. Several months ago, I was told that my daughters would be included in a very large upcoming family wedding, and of coarse I thought "Finally" since they are both adults. They were invited to the Bridal shower in July, which they each gave very nice gifts. But over a week ago everyone received there wedding invitation but to our surprise our daughters DID NOT. I checked my envelope and it read "Mr. And Mrs." thinking just incase they were cutting costs and mailed out one invitation for all of us. Although, our daughters are obviously grown and do not live with us and each have there own addresses. I have checked with several family members and they all received their invitations on the same day that I did. I am so offended that I`m seriously considering not responding, attending or sending at gift to this wedding since my daughters are feeling used (for an extra Bridal shower gift) and hurt. So please let me know is this proper or improper?