The genealogy is now defined: Souvenir de D. van der Gon X (Souvenir de H.A. Verchusen x President H. Hoover). However the code number of the pollen parent is .. wobbling (25.223 - 252.83 - 252.23)!!
I apologize for the previous wrong genealogy (my fault!)

The lineage is reported in the References.
And now I cross my fingers hoping not to find another one that contradicts it!!