how do you handle having "multiple social circles" and then friends with no mutual friends?

I'm the type of guy that prefers a few "close friends" than a bunch of not close friends. Over time i've accumulated small groups of friends such as;

• my past coworkers (hangout like once every 2 or 3 months)
• my current school mates
• my childhood/highschool friends group (hangout during breaks - holidays/summer)
• all the friends that i have no mutual friends with, just them.

There are some friends that I have no mutual friends with and I want to get closer to them but it just feels like if you dont have a "group" there is so many things you just cant do.

For example recently I went on a trip with some friends 2 hrs north to go snow boarding (highschool grp) but at the same time I want to share this experience with one of my friends with no mutual. (you can apply this to any situtation or experience I guess)

Or say you want to get closer or get to know someone more but they are used to hanging out with their own group, like their own group always sees the latest movies together.. or whatever and I just get discouraged thinking I for sure don't know any of those people and its just awkward if I try to hangout for eg a friend I know really well and another I dont at the same time.

tl;dr How do you become better friends when you and them have no mutual friends but both have our own separate circles??