United Kingdom, Jan. 23 -- Trace Cyrus and his siblings are "genuinely worried" for their father Billy Ray Cyrus.

The 35-year-old star has penned an emotional open letter after his dad's performance at Donald trump's Liberty Inaugural Ball on Monday (20.01.25), when the country music star was seen wandering around the stage and talking to the audience, which he later blamed on technical difficulties.

In a lengthy Instagram post, Trace - whose sisters are Miley, Brandi and Noah - wrote: "Since my earliest memories all I can remember is being obsessed with you and thinking you were the coolest person ever.

"I wanted to be just like you. The day you adopted me was the happiest day of my life.

"Sadly the man that I wanted so desperately t...