Is making a B list wrong?

OK heres the deal. My mother and I are having a little disagreement. I wanted to invite three of my cousins with their husbands. However, I am way over my limit. I was just thinking, maybe I should have them on a B list and when I get some NO's back I'll send their invites out. However, their parents will be getting their invite in November. Do you think they would know and be insulted if they didn't end up getting their invite til early december. They are going to sort of figure out they they really went out in November because their parents will have one. Would you be insulted to get an invite after the fact.
My mom says if we are going to invite them we have to know now so she can invite them to my shower. But I am trying to tell her they don't need to be invited to the shower, because they live in the Carolinas and obviously they won't come up for just the shower, so it would just seem like we are looking for a gift. What do you think?

I have a B list and there are people on it whose parents are on the A list and I don't care! I've already told my mom too (they're her guests). Maybe I'm just cranky today but I figure in that particular family all of the kids are married so they should understand the stress of it all, and if they get offended by being on my B list, they don't have to come.

I have way too many people on my list and I have to cut somewhere!