About data path of custom property group instances

By default, in custom property groups, their instance default data path will use an index.
For example, bpy.data.objects["Plane"].m3_particles[0].name

I would like to know if it is possible to instead use the name as the identifier in the default data path for my custom property group, as in this example?
bpy.data.objects["Plane"].modifiers["Array"].name