Question should he be called uncle to our baby?

My sister has a bf that she broke up an engagement 3 years ago and was with him the first time about 4 1/2years. Then they were broken up for about a year and a half and he reached out and crept back in. They were together again without him being around the family for about 2 years as it was awkward nobody cared for him… he just this year in March came back around the family… he seems to have changed a bit still not really a big fan but for my sister and my family for their daughter we are very welcoming to him because we don’t want to push her away. Plus he has been a bit more talkative etc. they have on their fb “in a relationship since 2013” to me that’s weird because their first time around was a broken engagement and nobody liked him at all. So many red flags. It should be the second stone around in a relationship since 2019. . . question is this… should he be called uncle Chris? Or just Chris? I mean she got me and my husband booties for baby and wrote from aunt Olivia and Chris. But idk