switching from secondary authentication to 2FA

In my Mac OS Mojave 10.14 at present the Apple ID is created with secondary authentication in the location system preferences - iCloud , also using the same Mac I had created two Apple ID using 2FA example one@ iCloud.com and two@icloud.com.

I know one Apple ID can be used at a time in Mac , but my mind changes I want to set up the first 2FA id one @icloud.com in my Mac and after few days I just want to set up second id two@icloud.com .

Then in the last ,set up the same apple id created with secondary authentication .

The reason for doing is sometimes my family members use this Mac , they need 2FA id or secondary authentication id and of course these ids should be set up in location system preferences - iCloud and not opening a new tab ( command and T ) and entering the appleid.apple.com and entering the 2FA id and password and then using the code on the trusted number .

A long clear steps explained in a very easy manner step by step so that there will be no mistake in establishing these ids on my Mac , and that will be highly appreciated and helpful .

Please post the answers .