Difficult to do with The "Online" software...you'd need three separate accounts.
the Desktop software allows you to create as many test files as you want..
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that being said, it is quite rare that MFS works out better than MFJ.
AND "newly married"..?..I hope you meant before the end of 2019. IF it was in 2020, then both of you have to file separate tax returns as "Single" for 2019.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*