FYI...I decided to run a test case and split the 1099R into two (as you suggested). One was for the 401K rollover to a Roth and the other a 401K rollover to an IRA. The Form 1040 pension taxable amounts (box 16b) were identical between the two methods.
However, close examination of the Form 1099-R Summary for the two approaches indicated differences in four items in the Pensions and Annuities section on Page 2. Although the Taxable amount of the distribution was identical, various values were either missing or different. The values shown for the split 1099Rs were correct based upon the descriptions for the related line items
Based on this data, I decided to proceed with the split 1099R approach that you recommended.
