No, Queen Frederika was not against. After "losing" Harald, he was the best option for Sophia to become Queen. And she explained in her memoirs that, when Prince Constantine told his parents that Prince Juan Carlos was interested in their daughter at the Duke of Kent's wedding, they were delighted.
Yes, Queen Frederika and Queen VE had a discussion , but about some details of the wedding, not about the wedding itself.
AFAIK, King Juan Carlos had a good relationship with Uncle Palo and Aunt Freddie.
I read somewhere, correct me if I'm wrong, that Queen Frederika was initially against her daughter, Sofia, marrying the then, Prince Juan Carlos of Spain. Moreover, I understand that Frederika and Juan Carlos' grandmother, Queen Victoria Eugenie (Ena), had a confrontation over this issue. So, with this being said, what was Juan Carlos' relationship with his mother and father-in-law?