Docker

I have my main compose file which has a bunch of services in and while it makes it easier to manage, it's also limiting when I wanna use postgres:// to access a database rather than exposing a port. I'm wondering if I can remedy this by moving it to a new network and(?) stack?

If so, is it just as simple as adding

networks
  - new network name
stacks
  - new stacks name

I'm still curious as to the answer, but it's not something I need.