Child Support / income tax dependent

I am divorced and now remarried and living in KY. I am paying child support on 2 school age children. At the time of our divorce they were both in day care. At this point they are not in full day care but an after school program. I was also working 2 jobs after we seperated in order to support myself and pay an agreed upon $$ for support before the divorce was finalized. I now am only working 1 job and need to know if I have any hope of getting child support reduced based on these 2 factors??
In addition, I would also like to know if I can press to claim 1 or more of the children on my income tax? Either swapping them off from year to year or having her claim 1 child
and I claim the other. What options do I have and since the divorce was finalized in MD with my ex now living in VA and myself living in KY where would I inquire?? Please advise?
Thanks