The mobi format has no support for series data. That is one reason to prefer ePub.
The normal way to handle this is to configure a plugboard to add the series information to the title metadata when saving to disk or sending to device.
https://www.mobileread.com/forums/sho...d.php?t=118563
And I say again: Use the fields in Calibre for their intended purposes. If that doesn't work for you, then you are doing something wrong.