How to get a handle to a Symbol Instance in a 3D Annotation Feature

Does anyone know how to get a handle to a symbol instance in a 3D Annotation Feature using J-Link ?

We can add a 3D Annotation feature containing a symbol to a 3D Model using a User Defined Feature.

But the symbol has different symbol groups. So after creation of the UDF, we want to set the correct symbol groups.

We can get a handle to the 3D Annotation Feature, but we find no way for getting a handle tot the DetailSymbolInstItem that this Annotation feature contains.