Roth IRA Basis Not Correct

[jonic]

I received one 1099-R which includes a taxable Roth conversion from my 403b to a Roth, and also a rollover from my 403b to a Rollover IRA (not taxable).   The gross distribution and taxable amount are combined for these two events on this 1099-R. When I enter the 1099-R, Turbo Tax asks me if it is a Roth Conversion. I answered yes, and it adds the entire gross distribution to my Roth basis on the Roth IRA Info Worksheet.  I only want the portion associated with the Roth to be included in the Roth basis, not the entire amount which includes a Rollover IRA which isn't a Roth. It doesn't appear there is a way to split it and when I go directly to the Roth IRA Info Worksheet it won't let me override it.  It is calculating the tax correctly but I didn't want this to cause me other issues later on. How do I fix it? The only way I could think of is to enter the 1099-R as two separate pieces but then it won't match what the IRS receives. I want Turbo Tax to have my Roth basis listed properly.

[jonic]

Note I have not filed the taxes yet.  Sorry I posted this in the wrong location.