In the years since we constructed the first vestigial "superapplier", our thinking about how to deal with relationships amongst the tree of models, and in general, https://fluidproject.atlassian.net/browse/FLUID-3674#icft=FLUID-3674 has changed - the original idea of composing a tree of cooperating appliers and models has emerged as just a special case of the requirements of what we now think of as the "model relay" system, now mostly described by https://fluidproject.atlassian.net/browse/FLUID-5024#icft=FLUID-5024 and https://fluidproject.atlassian.net/browse/FLUID-5045#icft=FLUID-5045. In this new model, models and appliers are essentially "isolated" and connected only by streams of ChangeApplier events, and we intend to cut down on cases where model objects are genuinely shared amongst multiple components (in the style of CSpace).

This issue is being closed in favour of the ModelRelay issues which cover all the use cases of this JIRA and several more - and in fact we should construct a separate JIRA for the removal of the existing SuperApplier implementation which will become redundant once ModelRelay is complete.