When reporting expenses for multiple (3) businesses, do I enter self-employed health insurance premiums in just one of them or split among the 3 businesses?

My wife and I have three businesses (I have 2, she has one) and we file a schedule C for each. I didn't think it appropriate to enter the full self employed health insurance premiums in each, so am wondering the right way to enter it.  We don't pay separate premiums -- just one for us both.  I guess I can enter the premiums in one of the businesses, but not the other two???