I work in TX, my spouse works in CA. We file federal as MFJ. I don't file TX state return but my spouse does CA. How to open the two 1040s side-by-side (MFJ & MFS/CA)?

[TomD8]

Be aware of CA's rule about filing MFS if you file your federal return as MFJ:

If you file a joint return for federal purposes, you may file separately for California if either spouse was
one of the following:
• An active member of the United States armed forces or any auxiliary military branch during 2020.
• A nonresident for the entire year and had no income from California sources during 2020.

Page 4, https://www.ftb.ca.gov/forms/2020/2020-1031-publication.pdf

Also, be aware that, since TX is a community property state, your wife must include half of your income on her CA return if she files in CA as MFS. 

Page 10, https://www.ftb.ca.gov/forms/2020/2020-1031-publication.pdf