In BibLaTeX specification, there are such required fields, that for example either "date" or "year" is required, but specifying both is not necessary. Same applies for example for @online type, where it is required to input either "author" or "editor". See e.g. biblatex documentation on CTAN, section 2.1.
I would like to have such functionality implemented, that one can specify to have one of multiple fields as compulsory so, that after any of those has some information, the others do not then have to contain anything.