I came across this interesting article about hierarchical structures within a multi-cat household and having several cats it made me think about our little pride. Our cats pictured are Willow (grey and white), Oliver (white), Oscar (white with tabby patches) and Lucy (tortoiseshell and white). They all have their distinct places within the group.
Willow is the cat we have had the longest. She first arrived as a 5 week old kitten with her brother Merlin, who we sadly lost in an accident at 9 months old. At this point we felt Willow needed the company of another cat so set about looking for a companion for her. I wanted a male cat of a similar age as I thought they would be more likely to create a bond. This is when I heard about Oscar and went to see him at the cat home. He seemed perfect, except for one small detail. He had to come with his brother Oliver. A sucker for rescue cats I decided to take them on.
Oscar and Oliver were feral when they arrived, they hated us and more worryingly Willow hated them. We keep the cats separate at first and gradually let them catch a glimpse of each other. Each time Willow saw the new cats, she hissed at them and made her feelings clear, she did not want these strange new cats in her home. This went on for several weeks and we had reached the point that I was seriously thinking of taking the new cats back to the cat home. Then one day when Willow was being particularly annoying howling during the night we shut her in the same room as Oscar and Oliver. The next morning we still had three cats and they managed not to kill each other.
Over the next month the three cats became to tolerate each other. Willow and Oscar quickly formed a close bond and starting sleeping together leaving Oliver on the fringe of the group. It was clear Willow was still the head cat as she would win all the fights between herself and Oscar. She now tolerated Oliver although it was clear he was lower in the group. Oliver was clearly also lower in the group structure than his brother, but the three cats would now sit together with Willow and Oscar together and Oliver on his own beanbag and occasionally all together as pictured.
At this point the group was complete and functioning well and I had no plans to introduce any other cats. This is when Lucy came along. She needed a new home and I once again gained a cat. Introducing Lucy was interesting. She was still a kitten and so much smaller than the other cats and we were worried they might hurt her. Willow and Oliver took an instant dislike to Lucy, Oscar the biggest of the cats was curious and keep trying to approach her. We kept the cats separate at night and introduced supervised meeting periods. During one of these Lucy was sitting on a beanbag when Oscar sat on top of her, she was now part of the group. Willow and Oliver still hated her but now that she been accepted by Oscar the others quickly began to tolerate Lucy. 
Now that Lucy was tolerated although perhaps still not liked by all, the group worked out a new structure. Willow quickly asserted herself as head cat, with Oscar second. Oliver and Lucy at this point appeared to have equal standing under the two larger cats. Willow and Oscar now spent much of their time curled up together and Oliver and Lucy although they don’t sit together spend most of their time playing together. The multi-cat household functions well, the cats live together happily with the odd fight but they all seem to respect their place within the group.