The `Glee` actress - who split from Alex Pettyfer earlier this year - and the `Captain America: The First Avenger` actor are said to have hooked up in February after meeting at a pre-Oscars party and she has already won his family`s approval.
A source told America`s In Touch magazine: "Chris` brother Scott is a huge fan of her show, and he particularly loves Dianna. He and his friends like to joke that as long as she stays on the show, the family will welcome her with open arms!"
Dianna split from her `I Am Number Four` co-star Alex at the beginning of February after dating for less than a year, even though the 24-year-old beauty had recently spoken about their exciting relationship.
She explained: "Alex might see himself as a bad boy, but he`s actually very sweet in real life.
"I think it`s important to have your differences in any relationship. I wouldn`t want to be dating a carbon copy of myself. That would just be boring."
Chris, 29, has previously romanced Jessica Biel and Christina Ricci.