Arnold Schwarzenegger's son Joseph Baena shared a sweet message of congratulations to his half-sister Katherine on social media over the weekend, after seemingly being left out of her lavish nuptials. The 29-year-old bride married Chris Pratt in a lavish star-studded ceremony in Montecito, California on Saturday, and shared a photo from the big day on Instagram on Sunday. In the caption, she detailed how the couple felt 'blessed' to be joined by their family as they became 'husband and wife in front of God'. Joseph, 21, did not attend the ceremony, but posted a kind note under the photo. 'Congratulations!' he commented, under his username, 'Projoe2', adding two love hearts and a bottle of champagne emoji. Scroll down for video Message: Arnold Schwarzenegger's son Joseph Baena shared a sweet note of congratulations to Katherine on social media over the weekend under his user name, Projoe2. Katherine married Chris Pratt in a lavish ceremony on Saturday, but her half-brother was not included While Katherine didn't respond back to the message, fans were quick to weigh in with their thoughts on the difficult family dynamic. One user wrote: 'I hope they invited you.' Another chimed in: 'He wasn't invited. I think Arnold is the only one that acknowledges him. Heart breaking.' While Joseph follows all his half-siblings on social media, none of them follow him back. Father and son: The aspiring actor and athlete was conceived during an illicit affair between Arnold Schwarzenegger and housekeeper Mildred Baena The aspiring actor and athlete was conceived during an affair between Arnold Schwarzenegger and housekeeper Mildred Baena. And while Arnold gave his daughter away to Chris Pratt on Saturday, however, Joseph was not in attendance. Joseph took to social media on Katherine's wedding day to document himself working out at the gym at Malibu's Pepperdine University. Not invited? Joseph took to social media on Katherine's wedding day to document himself working out at the gym at Malibu's Pepperdine University It's not the first time Katherine has come under fire for excluding her half-brother from family recognition. Back in April on National Siblings Day, she shared two sweet childhood snaps alongside her sister Christina, 27, and brothers Patrick, 25 and Christopher, 21. But many of her followers took to the comments to question why Katherine hadn't included Joseph. 'All hypocrites! They preach all this love, happiness, forgiveness, acceptance crap but yet they never ever acknowledge their youngest brother!! It's not his fault, he didn't ask to be born but he's here.' Where's Joseph? And it's not the first time Katherine has come under fire for excluding her half-brother from family recognition. Back in April on National Siblings Day, she shared two sweet childhood snaps alongside her sister Christina, 27, and brothers Patrick, 25 and Christopher, 21 User rosa_hdz_fashionista continued: 'And if you notice Joseph always likes all their photos and follows them. But They always like most of Arnold's photos except the ones with Joe in them.' At the time, Katherine hit back at the commenter reminding her to be kinder with her words. '@rosa_hdz_fashionista saw in your profile it says "god always". Just wanted to remind you of Gods presence in all of our lives and even in yours as you come spreading hurtful words and judgement. 'He does not judge you or any of us. I am praying for you and sending you love not because what you said is okay, but because i believe you need love to heal whatever is causing you to post comments like this. god bless you!' Kindness first: At the time, Katherine hit back at the commenter reminding her to be kinder with her words All better? 'It's a very tough situation for him. It's a very tough situation for my kids. Very tough situation for my family. It was tough for everybody. But it has happened and now we have to figure it out, right,?' Arnold said in 2015 The children's dad, Arnold, 71, has continued to be open about the uncomfortable situation, telling Howard Stern in 2015: 'He's [Joseph's] terrific and he totally understands the situation.' 'So, it all has worked out. It's a very tough situation for him. It's a very tough situation for my kids. Very tough situation for my family. It was tough for everybody. But it has happened and now we have to figure it out, right?' Katherine's mother Maria Shriver separated from Arnold shortly after the affair with Mildred was revealed. The former Governor of California is still technically married to Maria. They separated in 2011 after marrying in 1986. Mother and son: Mother and former housekeeper Mildred is still close with Joseph All rights reserved for this news site dailymail and under his responsibility