If MC is not on Layla or Lexi's path, you don't end up having dinner with their family so aren't directly invited.
If MC is still one of Layla's best friends, she'd likely invite him.
On Erynn's path, she'd probably want MC to go as well. Unless Lexi hates MC?
On Elena's path, would Layla want MC there if she hates him?
If Layla or Lexi don't like the MC, there'd be problems getting him invited I think.
On Val, Nikki, or Cara's path, would it be easy to sell MC getting an invite? Might depend on Layla's points.
If MC is involved with Tori, would Layla want him there?
There's a lot of states and variables to account for before the BBQ or Party could happen.