Can a non custodial parent put a restraining order on the custodial parent's spouse for previously abusing the child? There are police reports and the spouse was charged.

Either parent can get a restraining order against the other.

If you want a restraining order keeping the other party away from YOU, then you would file in your local City/Town Court, asking for a restraining order and presenting proof.

Or are you asking how to keep that parent away from the child?

Keep the other parents spouse Away from child

I suspect the court, if asked for a restraining order, would say that one is not necessary: the step-parent has already been charged with a crime and, if convicted, that should suffice.

Also, such an order, for the step-parent to keep away from the child, would have the effect of separating spouses. Perhaps a better solution would be a change in primary physical custody?

We have already fought in court and did not win. But we suspect there is abuse going on again.

You can't get a restraining order without proof. Police Reports and arrests are not proof if the person was found not guilty.

Suspecting and proving are two different things.

You have opened several threads about this same problem. Here's one of them - https://www.askmehelpdesk.com/family-law/parenting-plan-not-followed-458297.html.

If the other party has an Attorney your reports continue to be determined to be groundless you could very well be opening yourself up for legal action.