I've always been fascinated by the names of groups of animals. (Think a murder of crows, or a pack of coyotes.) My sister and I used to come up with names for groups of people or pets just for fun. For instance, my brother's name is Robert so we decided that if there were a bunch of Roberts in a room (which often happened at family gatherings), they would make up a squattle of Roberts. I don't know why we came up with 'squattle' but it really seemed to fit at the time.
I've recently discovered the wildly popular and fascinating Good Job, Brain podcast. I've listened to only a small portion of the available episodes, so far, but I've learned some pretty awesome stuff. Most episodes focus on one specific subject and the hosts teach and quiz each other while the audience gets to listen and play along. They've had a few episodes about animals wherein they talked about what groups of animals are called, even going so far as point out that should you ever run across a group of unicorns (as you do), you can refer to them as a 'blessing.'
Asking someone what a group of them would be called is one of my favorite break-the-ice questions. In fact, I got my name on The Flog when I wrote in and asked Felicia Day what she would call a group of Felicias. (She says if she had a group of clones, which she most certainly does not, they would be called a Felicitude. I've got her signed letter framed in my living room!) If they can't think of a name for themselves, I like to ask what they would call a group of their favorite pet. I've come up with names of groups of my cats and it's fun to talk through these things with people.
The best way to go about naming groups is to think of the most notable traits of that person or pet and consider synonyms or related words. I think certain words sound like they could mean a group, and other words don't work at all. My cat Martin, for instance, has many traits. Some of them are even good! The most notable ones, though, are that he's very demanding, very vocal, pushy, orange, and that he's getting to be pretty grumpy in his old age. Considering all this, I decided I like the word 'scream' for a group of Martins. My ex thought a 'screech' of Martin's sounded better, but I disagree. I don't think screech sounds like a group word, whereas I can imagine a stuffy professor teaching his class all bout the scream of Martins that tore through a small fishing town in Maine, demanding they be given free tuna.
My friend's cat Maxwell is a bit of a handful. He's kind of like Martin if Martin was chaotic evil rather than chaotic good. Maxwell tends to be pushy and selfish and aggressive. We've made many a joke about how, were he actually able, he would blackmail, steal, bribe, and cheat his way into getting whatever he wants. I've decided that if there was a group of Maxwells (god forbid!) they would be called an extortion.
Think about what you might be called if you had a group of yous, Orpan Black style. If that doesn't interest you, think about what you might call a group of your favorite pet or family member.
I think a group of Olivias would be an ambivalence. An ambivalence of Olivias.