Connecting Main & Sub Plots

I’ve done enough prewriting work on my new novel to know a lot about it. But today, as I worked, I realized that I know the main plot, but not the subplots.

This is a complex story, with about 12 character who need to be clearly delineated. There will be about 5-6 subplots going on between characters and they need to be clear, need to have a connection to the main plot, and need to have minor arcs of both plot and emotions.
Because of this complexity, I feel the need to clarify in my mind those subplots before I start. When I laid them all out, I found that they seemed disconnected.

Subplots must support or reinforce, contrast or counterpoint, the main plot and intersect at important points of the story. If there’s more than one subplot, there should be variety with some supporting or reinforcing and some contrasting or counterpointing. Variety is what’s needed.

I looked at my subplots to see if I could categorize them in some way. I found that I am playing with the idea of identity or self-image. Do we define ourselves by our education, body image, entertainment preferences (TV, food, music) or by ethnic differences? The main plot says we define ourselves in terms of our families. So, these subplots work. My tasks will be to make sure they refer back to self-image/identity without being too overt, and to add variety among them.