Parentage is contained in the plant patent filed pp23122
Unnamed seedling mother and unnamed seedling father.
Here is the quote:
The new variety of rose plant of the present invention originated from a controlled crossing in a breeding program of two distinct parents during the summer of 2000. The crossing was between an `un-named seedling`, and an `un-named seedling`.

The resulting seeds were planted during the following winter. The resulting seedlings were evaluated and exhibited distinctive physical and biological characteristics. The new rose plant was selected as a single plant from the seedling beds due to its superior characteristics and asexually propagated for further evaluation. This new and distinctive rose variety is named `KORschwill`.

SUMMARY OF THE INVENTION

The new rose plant may be distinguished from its seed parent, an `un-named seedling`, by the following combination of characteristics: 1. The flower color of `KORschwill` is velvet red while the flower color of the seed parent is dark red. 2. The disease resistance of `KORschwill` is excellent while the disease resistance of the seed parent is only good.

The new rose plant may be distinguished from its pollen parent, an `un-named seedling` by the following combination of characteristics: 1. The flower color of `KORschwill` is velvet red while the flower color of the pollen parent is pink. 2. The growth habit of `KORschwill` is moderately upright to bushy while the growth habit of the pollen parent is upright.