"I absolutely approve! Steve will be an amazing husband to Anna and a great brother-in-law," Andrew Paquin told PEOPLE at Saturday's Tribeca Film Festival premiere of his directorial debut movie, Open House, which also happens to star Anna Paquin and Stephen Moyer.
Assuming the role of the protective older brother, Andrew, 33, has no problem with the 40-year-old English actor marrying his 27-year-old sister. In fact, Andrew and Moyer have become close buddies themselves.
"She's in very good hands," says Andrew. "Steve's a lovely man and a really great guy. He's become a very good friend. Everything is great and I'm really happy for them."
A psychological thriller, Open House was filmed in Andrew's own home – before his sister and Moyer became engaged. Still, the director says he saw something special brewing between them.
"They have amazing chemistry together on and off the screen. There's something special going on, and they understand and respect each other."
Now with their plans to tie the knot, "They are certainly in love and very good to each other and very kind to each other," says Andrew. "That's important."
And while, like all siblings, they fought while growing up, when it came to directing his Academy Award-winning sister, "It was fantastic … but I was nervous because she's such a good actress," he says.
"We only had two days together and it was my first time directing and I wanted to do a good job. But she made my life pretty easy as a director. She knows her lines perfectly and she understands her character."