Can you get health insurance for a dependent that doesn't reside with you?

I have a four yr old son that I've had health insurance for since he's been born. Me and his mother don't leave together and now my job has a new insurance and there trying to cancel him bc I don't have proof besides my name being on his birth certificate. I help his mom pay for aftercare but of course it's in his mom names bc we leave in different states. Is there a law that if my child doesn't leave with me I can't provide health insurance.
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health-quotes.isgreat.org - here is my health insurance plan. As I remember they can provide such a service.
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