child support payment when stationed in Germany? OHA w/BAH or no?

This is for sure a question for your civilian attorney.  If you are on court order child support, and the BAH is included in the calculations it is possible for it to go up or down.  That would also depend on the law in the state you are paying Child Support for.  Generally the Army provides a completely different BAH rate (not the normal BAH) for child support purposes.  That said, I am not legal so my best advise is talk to your civilian attorney who is BARed in the state you owe the child support.

First, are you are your previous spouse on terms to discuss?  I am assuming that isn't the case. Therefore, in order to address your question you need to seek legal advice as soon as possible in order to insure you are correct.  Take a look at AR 608-99 as well.  Best case is to provide your previous support amount until you determine the correct amount or receive it in writing.  Never assume anything that is not presented and justified by legal.  Expect your previous spouse to file an IG complaint or congressional if there has been a reasonable amount of time without payment. Keep receipts, documentation, and I would suggest you make memorandums for record as a personal account of your situation---date/time/signature.  At that point, you will only need to explain and provide your commander with the facts and will not face adversity. 

Stupid question