Prince Frédéric Prinz von Anhalt Says Son Kevin's Adoption on Trial Basis

Prince Frédéric Prinz von Anhalt, widower of Zsa Zsa Garbor, says the perfect son he just adopted to carry on his royal legacy is on a short leash ... and could get the boot at any moment.

We caught up with Prinz Tuesday after his lunch at Il Fornaio in Bev Hills, and he broke down this adoption ... saying Kevin Feucht was the perfect fit of several options, and he's happy with his choice. For now.

He even said Zsa Zsa would like Kevin too -- they'd actually met back in the day, and Prinz said she'd tell Kevin ... "You're so cute. I want to adopt you."

But, then Prinz told us nothing's written in stone here. He says Kevin's gotta keep performing at a high level if he wants his inheritance and title.

As he put it, "If he's bad, I get another one. If the other one is bad, I get another one. I can adopt as much as I want."

As we previously told you, the 78-year-old prince decided to legally adopt 27-year-old Kevin to inherit his estate and keep up his lineage that dates back some 1,000 years.

In exchange, Kevin will live with his new dad and take care of him -- this includes things like cooking for him, doing chores and making sure his bills are paid.

Nothing in life's free, right?

The whole family affair is being filmed for a new A&E series.