Sometimes groups can work however it usually causes multiple problems. In the group you saw, not sure how young were the babies and how old were the adults. Were the adults all spayed/neutered? Were the "babies" fixed yet? Were there a mix of males and females?
Babies can begin to be fertile as young as 10ish weeks of age-- not a good idea to have intact rabbits interacting if one doesn't want them breeding.
Hormones cause major issues like fighting -- again, not a desired result.
There are numerous factors that play a role in whether or not rabbits will get along-- whether in pairs or in a group.
As a whole, the general consensus is that rabbits do best in pairs (fixed and bonded). But even getting 2 rabbits to bond can be a tricky affair. Some bonds will go easily and without effort. Others take weeks or months of monitored interaction before they can be considered fully bonded.
The key to long-term, successful bonds is having both rabbits fixed. With hormones eliminated, the bond is more likely to remain stable.
Here's a further link on bonding rabbits:
https://rabbitsindoors.weebly.com/bonding-bunnies.html
And here is a more detailed look at groups and a quote from the article. If you click on the following link, you'll need to scroll way down to the section on "Rabbits Groups and Trios."
"Whilst most experienced and knowledgeable rabbit owners and professionals agree that the best social arrangement for rabbits is to keep them in bonded neutered pairs (usually male/female), there are some situations where a trio or group may be attempted, with varying degrees of success. In this article we will look at various options to give such an arrangement the best possible chance of working. "
http://cottontails-rescue.org.uk/information/bonding-bunnies/
