During family conflicts, such as the famous succession scandal regarding the questioned legitimacy of the Crown Prince in 1778, he and his sister were on their mother's side against that of their brothers Charles and Gustav.

He was given a minor role in the Revolution of 1772 of his brother Gustav III, who gave him the task of agitating in Södermanland and Östergötland.

During the great succession scandal, the so-called Munck Affair in 1778, when the queen dowager Louisa Ulrika questioned the legitimacy of the Crown prince in reference to the rumors that Gustav III had convinced Adolf Fredrik Munck to impregnate the queen, Sophia Magdalena of Denmark, Frederick sided with his mother and defended her before the king by pointing out that these rumors had not been invented by their mother but were in fact widespread rumors, and he reportedly said to his brother the king: "The entire city is talking of it, and it is commonly believed that You are not altogether man, and that it is because of this reason, that You have enticed the Queen to it to have an heir to the Kingdom.

[1] His sister-in-law, Hedwig Elizabeth Charlotte of Holstein-Gottorp, describes him as beautiful, with expressive eyes, an easygoing temper, and very handsome when he dresses properly, though often badly dressed in his private life, and gives the estimation that he would have been a greater social success, if he did not say so many suggestive things and had such a filthy mouth [that is to say, he used a sexually suggestive language], which he acquired because he had spent too much time with men, and had such a weakness for women and sex.

In the autumn of 1789, Hedvig Elisabeth Charlotte prepared to depose Gustav III and place her husband Duke Charles upon the throne.

[3] Her ideal was the Swedish Constitution of 1772, which she saw as a good tool for an enlightened aristocracy, and the war and the Union and Security Act had made her a leading part of the opposition.

She and her father refused, as they were afraid that she would be badly treated by his brother and mother, who were reluctant to give their consent, and because she was already engaged, and Frederick Adolf was sent to Italy in 1776 until she was married.

The King gave his permission to the marriage with the condition that it was postponed for a year, during which Wrangel was sent to Scania, with the thought that his brother would change his mind when the time was up.