This is becoming a growing topic of concern. I have been to two presentations where the accuracy calculations have been stressed. If you are working with a financial advisor they should be well informed on the rules and regulations.
How the funds are titiled does have an impact on how many distributions are necessary. If funds are kept in a 401K or a 403B, theses need to be separate distributions for all of the collected traditional IRA’s.
If you made an error in taking your RMD you can request a waiver from the IRS on form 5329. But this is no guarantee of a waiving of penalties and interest. This also needs to be filed timely. Remember the penalty can be as high as 50% of the distribution.
I had a client who requested his RMD, but the Broker Dealer he was working with did not process properly. I filed the waiver and we have a signed letter from the Broker Dealer on their letterhead. SO I think we are in good shape for waiving his penalty. But this year he has to recognize both distributions so the tax impact may also be higher.
If you or your parents are handling these calculations yourself good luck. I recommend working with a financial advisor or CPA for assistance with the calculations.