I can't recall to have ever seen a trio of maroons in pictures from the wild, only pairs.
While most other anemonefish species will allow juveniles to coexisted with a mature pair in a large enough anemone, maroons seem to be different and do not allow juveniles besides the resident pair. Juveniles might be hanging out in near by smaller anemones if there are such around.
The most tolerant anemonefish species towards conspecies and other species of anemonefish are clarkii, and maybe some of the skunks. All others are more likely to kill off unwanted extras.
Those that manage to keep a large number of ocellaris or percula in a tank are usually successful because they started out with a batch of juveniles (most of the time from the same hatch) and because the numbers of fish make it difficult for the dominant pair to single out one.
But even this approach is highly unlikely to work with maroons.
I've bred them once and as soon as the larva are through metamorphosis and have the adult coloration they start fighting among each other. I lost all but 5 of that hatch before noticing that.
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