Reflecting partial year foreign income with a single W-2 for the entire year

I received severance for the entire year (Jan 1 - Dec 31) of 2019 which is reflected on a single W-2 from my former employer in the US.  I moved from the US to the UK Sept 2, 2019, expecting to live there 3 years so am now a tax resident of the UK.  I understand the severance received while I'm in the UK (Sep-Dec) is considered foreign earned income and is eligible for the Foreign Earned Income Exclusion once I pass the physical presence test.  (I'm filing form 2350 to get an extension to October 2020 so that I can file my return after ensuring I meet the test.)  How can I make TurboTax reflect the US and foreign income amounts accurately when they are from a single W-2 for the year?  It's currently treating the entire W-2 amount (and then some) as foreign income rather than just the income from Sep to Dec.  Thanks for your help.