IIRC romancing Carrie is almost the same as romancing the other three packmates (Marco, Ed, and Vicky), always be nice to her, spend every free time with her whenever possible, and don't date anyone else.
As for Roe, you can't be the alpha (they will hint at it during the convo in the bar since other alpha cannot date other alpha), be nice to them, spend free time with them whenever possible, don't date anyone else, and don't be antagonistic with the other pack especially when it was discovered your Alpha was murdered.