Invitation for two - Can I ask my daughters to go instead of my husband and I?

I just received a print out invitation addressed for my husband and I. Included in the invitation was a small piece of paper that read two per invitation. There was no rsvp request.

The invitation is for my aunt's fifith wedding anniversry. My father will be coming in for the event as well as my sister. I want to honor my aunt's request and have decided to ask my daughters who are now 18 (a senior in high school) and 19 (a senior in college) to attend the anniversary ceremony in my place and my husband's place.

Even though the invitation was addressed to my husband and I, would I be in the wrong if I were to ask my daughters who are now 18 (a senior in high school) and 19 (a senior in college) to attend the anniversary ceremony in my place and my husband's place. My youngest does not feel that this is a nice party as family members are being excluded. The invitation also read that the party is being given by her children, grandchildren and great grandchildren.

Should I send best wishes and regrets, if I do not attend, or do I need to if there was no rsvp.

I am also hesitant about attending since my youngest expressed mixed emotions when she saw the piece of paper that read two per invitation. She even stated that they did not want young people there as they were not 21.
I assured her that it was the aunt's party and perhaps' there is not enough space in the hall.

Thank you for your response.