This switch is available as a checkbox under:

Options > Project Options > General Project Options > Change ownership of non-navigable association

The following image example illustrates the effect of the switch:

• = true: Properties that were owned as a non-navigable of an Association become owned by the Classifier at the Assocation end when navigability is switched from non-navigable to navigable. This it the default, and what most users might expect.
• = false: Properties that were owned as a non-navigable of an Association remain owned by the Association when navigability is switched from non-navigable to navigable. This is an expert mode, and users should be particularly careful when using this mode.

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