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1,2, & 3 depend on domicile. My guess would be she left LA with no intention of returning - since separating. Only LA income would be taxable to LA and considered community property. The MD return may be a nonresident since she passed through so quickly. Then you could file a part year LA and part year PA.

However, we need to get this right, no guessing! Let's start here  Publication 555 (03/2020), Community Property - Internal Revenue Service and work through this. When she left LA and moved to MD, did she know it was temporary or was she intending to move on to PA or to return to LA? If she left LA with the intent to not return, she would have left LA and the community property behind. Did she get a MD or PA license or register her car or voting? Anything to look like LA was in the past?

The pub states:

If you move into or out of a community property state during the year, you may or may not have community income.

Factors considered in determining domicile include:

• Where you pay state income tax,

• Where you vote,

• Location of property you own,

• Your citizenship,

• Length of residence, and

• Business and social ties to the community.

To help determine, see What is my state residency status? Once you have determined if LA was indeed left behind when she left, then you can determine which jobs were LA resident. 

• She may have been a LA resident but not domiciled there for the MD job. If so, MD income goes to LA income.
• IF LA was not a place to return, then MD income would not be in the LA return.

Now that you have domicile figured out, we can look at Pub 555 which states: Community income.

Generally, community income is income from:

• Community property;

• Salaries, wages, and other pay received for the services performed by you, your spouse (or your registered domestic partner), or both during your marriage (or registered domestic partnership) while domiciled in a community property state; and

• Real estate that is treated as community property under the laws of the state where the property is located.