I created a custom product variation type named "Variante preparate" with the machine name "preparate" unchecking "Create matching product display type"
I referenced it (link it) mannualy in the custom product display type named "Afisaj Preparate".

(to help you understand better the exact situation:
Afisaj (romanian language) = Display ;
variante(ro) = variants ;
Birou Administare(ro) = Administration Office)