Brielle Biermann says the only sign of Kroy on her wedding day might just be her last name … because she has no idea if he even plans to show up.

Photogs got Brielle at LAX on Tuesday … and they asked her if both Kroy and her mom, Kim Zolciak, planned to be at her wedding despite their nasty divorce.

Check out the clip … Brielle says she can’t answer that question — because she hasn’t heard from Kroy in a while, and she’s got no idea what he’s got up his sleeve.

As you know … Kroy married Kim back in 2011 when Brielle was still a teenager — and she legally changed her last name to “Biermann” in 2013 after Kroy formally adopted her and her sister Ariana.

Brielle got into the drama between Kim and Kroy as well … stating outright that she doesn’t think her mother should lose custody of the 4 minor children she shares with Kroy — pointing out she and Ariana turned out just fine with their mother’s parenting.

Remember … Kim lost temporary physical custody of the 4 kids a couple months ago after Kroy accused her of neglect and claimed she’s “more selfishly concerned with her own image and her work options” than their children’s well-being.

Brielle ends the chat with some harsh words for Kroy … saying she thinks the dude needs help — and admitting she hasn’t been happy with his recent interactions with Kim.