Hey!
It sounds like you already have a lot of colors established. I would pick the favorite of the colors already present and play with tones (for example pale pink, or lavender) in accents around the room!
Although CloeCouture’s living room is all gray, it’s a great (hehe) example of how you can pick one color and play up different shades of it so it looks balanced. We have light gray, white, silver, charcoal … the full gamut!
Hope this helps!
XOXO,
Kate