Your concerns are well-founded. The standard for altering custody waas changed by the Ellis decision a few years ago, and furthe refined by last year's Rivero case. Both, along with the statutory list of factors, and all relevant legal tests, flowcharts, etc., are posted at http://www.willicklawgroup.com/child_custody_visitation. You should, first, review those materials.
Was a motion filed? If so, you are already in process for that which can be done. If not, consider it. Have you considered, based on the neglect and abuse allegations, talking to CPS?
You should probably seek consultation with an appropriate family law specialist. I would suggest starting your search with the American Academy of Matrimonial Lawyers, the Nevada chapter of which can be viewed at http://www.aaml.org/go/fellows/fellows-by-state/?showResults=true&state=NV.
If you decide you would like to discuss this with one of the attorneys of this firm, please take a look at our consultation policies, procedures, and costs, at http://www.willicklawgroup.com/consultation_policies.
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