Unlike ProSeries Professional, ProSeries Basic does not have a MFJ vs MFS Comparison Worksheet.  However, you can use the What-IF Worksheet to create a comparison.  To do so:

1. Open the tax return.
2. Press F6 to bring up Open Forms.
3. Type Wha and press Enter to open the What-If Worksheet.
4. Use Column 1 for the original Married Filing Jointly return
5. Using Column 2  to manually enter the taxpayer's information
6. Using Column 3  to manually enter the spouse's information

Another way to do it is to create two copies of the MFJ return.  Change the filing status to MFS for both copies. On one, delete the spouse and of their related entries.  Change the amounts of any items that are going to be split.  For the second, delete the taxpayer and copy the spouse to the taxpayer.  Then delete all of the taxpayer entries and change the items that are being split.