Instrument families are categories of similar instruments whose staves are typically bracketed together in scores. For example, violins and cellos are both in the string family, while flutes and oboes are both in the woodwind family.
In Dorico Pro, instrument families affect which staves are bracketed together by default, where system objects appear, and the order of staves in scores. Instrument families are also used to organize instruments in the instrument picker.
Each instrument must be included in at least one instrument family, but can be included in multiple instrument families. For example, the Electric Piano appears in both the Electronics and Keyboards instrument families.
You can create and edit custom instrument families in the Edit Instrument Families dialog.
You can determine the positions of instrument families relative to each other by creating and editing instrument score orders, which you can then apply to projects.