Joseph Baena Likes Katherine Schwarzenegger's Shout-out to Chris Pratt

Katherine Schwarzenegger's praise for fiance Chris Pratt is obviously something their fans are here for, but one "like" in particular stands out among tens of thousands -- the one from Joseph Baena.

Katherine's brother from another mother made it clear he's a fan of her engagement to Chris Friday, with a double-tap on her IG post. Kat was shouting out Pratt and encouraging fans to go check out his new film, 'The Lego Movie 2.'

Joseph's "like" could signal a big shift in the House of Schwarzenegger. As far as we know, Arnold's kids with Maria Shriver -- Katherine, Christopher and Patrick -- have never had a relationship with Joe ... whose mom is the housekeeper with whom Arnold had an affair.

It's possible they've connected away from the spotlight -- or it could just be that Joseph's using social media to extend an olive branch.