Suppose I have a tagged equation defined in an
align environment, labelled using command
Now I write another equation, but I want it tagged with the same number as the first equation plus a bespoke suffix, e.g. if the first equation is tagged (12), I want the second one tagged (12-2) or (12-b). I also want the suffixed tag to display as such if I reference the equation.
How can I achieve this?