I am not sure if you identified the model numbers correctly in your problem statement as your model 3 and model 5 are not close to each other and do not share nodes. Anyway I think your main question is to generate a connecting mesh between two regions which have different mesh density. To demonstrate that, I have defined a new mesh model named Bentley 1 connecting the models 1 and 2 and another mesh model Bentley 2 connecting all of the individual models.
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