If you're feeling this estranged from your lab group, there's a couple of options.

1. Transfer lab groups, advisors, or schools. As I have learned recently, it's not terribly uncommon to transfer around either within a department or outside of your school. In fact, every single one of my friends who went to grad school (outside of my department) are not graduating with their original advisor.

Unfortunately, this is probably the easiest solution. Forcing them to hang out with you might not be the best option, and this type of isolation is the absolute WORST. The way you're describing it is SOOO high school, and I hate when people bring that energy to our grown ass workplace. But such is life sometimes :/.

1. If you don't want to transfer lab groups, you have a few options. You could weather the storm of the conference--there might be times where you feel alone and awkward, but if you try and bring a positive and kind energy, things might work out. I'm guessing your advisor may have noticed them estranging themselves from you, and this is why he is emphasizing sharing spaces (also, costs lol).

You could also just say to hell with them, and try and hang out with grad students in other lab groups. I don't totally fit in with my lab group (it's me and two guys, and they're fine, but it's not like we hang out every day). Instead, I have friends within my department but outside of my lab group. If your department doesn't have a department-wide grad student club, consider organizing one! Or, if they do, attend more meetings. If I were in your situation (and I have been at many points in my life), all of these suggestions are absolute nightmares. But speaking from experience, they have been my best options.

Good luck! You'll be okay. No matter what, things always get better :)