You can file Joint because you are married. You have to agree to file Joint. You have to enter each spouse's info and income on the Joint return. How you enter it is up to you. If you use the Online version then I guess each spouse could log into the account to enter their income. You would both need the username and password. Then coordinate who enters what and when.
WHEN 2023 is available......
To compare Joint to MFS. If you are using the Online version, do NOT change anything on your return. You would have to start with a new account and do a test return. You don't have to pay unless you want to print it out. So you might need 3 accounts, one for Joint and two MFS, one for each spouse.
How to Compare Joint to Married Filing Separately
https://ttlc.intuit.com/community/married/help/how-can-we-compare-married-filing-jointly-with-marrie...
How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
It would be better to use the Desktop CD/Download program. It can do unlimited returns and has a What If worksheet to compare them and many other advantages over the online version.
You can buy the Desktop CD/Download program here
https://turbotax.intuit.com/personal-taxes/cd-download/
