Pacifica: You're family love her! They loved how adventurous and funny she is. They like how she isn't shy and is very social and gets along with everyone.
Dipper: They thought he was a bit cocky at first, but they learned to accept him. They find him interesting and his jokes can be a bit funny sometimes. Surprisingly, he's also good with children. He's very sweet and gentle with you're little cousins (and/or) siblings. Makes you wonder how good he'd be as a father...
Mabel: They liked how she was sassy and competitive. They had a weird feeling from her but accepted her sooner that you expected. She also, surprisingly, is an amazing cook and enjoys helping you're mother in the kitchen. You had some of you're cousins drooling over her but she always made sure you knew, she only had eyes for you.
Will: Soon after he was free from the Gleeful twins, they were surprised that you had feelings for him. It took them a while, but they accepted it. Dipper and Mabel couldn't promise that they wouldn't tease him a little. But he liked you're side of the family. They found it cute how shy he was. He is also good with you're little siblings (and/or) cousins.
Gideon: They adored him! They found him adorable about how passionate he was about you and you're relationship. He also enjoyed making pies and cakes for you're family which to them, found it as a good free meal once in a while. But anyways, yes, they like him.
Scarlett: They like her and don't like her at the same time. They find her pretty cocky and a bit of a showoff. They say her jokes can be a bit inappropriate but she can sometimes be hilarious and bring a smile to their faces. So basically, they enjoy her and they dislike her at the same time if that makes sense.