The KISS frontman was sad that he couldn't mark William Eisen's century of life in person due to the social distancing measures in place to slow the spread of coronavirus but the 68-year-old rocker urged his fans to send happy birthday messages to his father instead.
In identical Twitter and Instagram posts, he wrote alongside a phoo of the two of them together: "MY DAD IS ONE HUNDRED YEARS OLD TODAY! He Is An AWESOME Man And I Am So Proud To Be His Son. We Can't Be Together Since It's Not Safe. I Love Him Dearly And Am Asking EVERYONE PLEASE WISH HIM HAPPY BIRTHDAY ON THIS MILESTONE. Thank You. (sic)"
Among the thousands of fans to send birthday messages to William was magician Criss Angel, who used his post to also praise the 'Crazy Crazy Nights' hitmaker.
He wrote: "Happy 100th Birthday! What an amazing milestone.
"Btw you brought an amazing son into the world -- the fruit doesn't fall far from the tree. All the best and here's to another hundred.(sic)"
A few weeks ago, Paul promised to share his songwriting process with fans as he was going "a little bit crazy" self-isolating at home.
He said: "My plan tomorrow is to sit here, get a guitar, maybe tell you some stories, maybe show you how I wrote a song -- show you how I wrote 'Love Gun.' That could be interesting 'cause I need to connect with you 'cause I'm going a little bit crazy."
As promised, he shared a video of himself talking about the song the next day and also found the time to praise medical workers.
He said: "Big thanks to all the people who are on the frontlines trying to get us through this.
"[I've been home for] 17 or 18 days because that's what the medical people, the experts, are saying we should do -- try to take some of the strain off the doctors and all the hospital workers, try to flatten that curve.”