Django: maintain sessions across multiple domains

I have two/multiple domains say, foo.com and bar.com and both have the same backend, which means both domains redirect the coming requests to same "web instance" hosted somewhere else.

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Current Behaviour

If a user login in foo.com, he/she also need to login in bar.com in order to access any end-point/URL such as bar.com/some/url/end-point/.

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The SESSION_COOKIE_DOMAIN may do something if I've the domains with a common pattern. Unfortunately, I don't.

Question
How can I maintain user sessions across multiple domains?

from Django: maintain sessions across multiple domains