Back on topic: I think Silvia and CG both spoiled CP way too much to compensate for his birthright being stolen
Silvia seems like an old fashioned lady who treats men and women differently because that was how she was raised and then she married a misogynist who reinforced her lopsided view of the sexes. Add to that the fact that some women see their daughters as competition for attention and it's easy to see how she could have preferred and coddled CP leaving him emotionally and mentally soft and spoiled and really handicapping him in his ability to make logical life decisions. JMO
I always felt that Viccan was the "odd one out" and ITA with what you said. In the 70s and 80s Silvia was incredibly popular in Germany, I remember one day how my mom bought a magazine with an interview and Silvia explained in it that there were only sweets one day a week and a very limited amount of them for her kids. I was a kid back then and Viccan is way younger than me. My mom and her friends were so impressed that they tried that ... for us it was a few sweetless weeks, then summer rolled on and we had way too much ice cream again.
But I think Silvia always thought that she would be judged and measured on how well Victoria would turn out - which IMO let to so much pressure amd restrictions on Viccan that she imploded and started obsessivly self-controlling which ended in a eating disorder.
Silvia and CG tried to get rid of Dan by trying not to accept him (remember how he had to stand in the crowd at Viccan's birthday and other things). Dan was simply "not good enough". Basically Viccan did the same as CP - she chose an unsuitable partner - but other than her brother she picked someone who loved her so much that he just hung in there and waited through all the opposition. As his "deficites" were only education wise, things turned out great.
As you said ... she does not perceive the snakes deficits as so severe ... because she is a woman. But a woman marrying "down" instead of "up" like Viccan did was against Silvia's view of the world.