There has been a longstanding problem for academic reference collections with how best to manage the common sequential scenario of a conference paper, maybe also published in abstract form in a journal, then sometimes appearing on a preprint server, subsequently published online by a journal (but not always; and maybe/maybe not with a DOI), finally followed by 'full' publication (when it finally gets a volume/page numbers, although you may not notice that transformation has happened).

You will likely have entered some or all of those as individual items at different times. At best currently you can then use Zotero's Related tab to link them manually, if you recognize that they are basically the same work (although you might also choose to delete the earlier, less complete versions). The problem with that is that you later have to click on the Related tab of such an item to see if there are any related items there (there is no 'count' to alert you in the Related tab title). Also, the Related tab may of course be used for other things, like other papers cited by the item (that you already have in your library).

I agree with @anders221 that there ought to be a better way of dealing with this. Maybe a "composite" or "parent" item type, under which all of the above could be filed. Perhaps a different kind of 'merge', that keeps all of the individual items (also kind of like a sub-collection). It really needs to be something in the main library pane, not just in the right pane (like Related).

A similar problem exists for multi-chapter books, which would often all best appear under their book parent, not as separate items. Also, the ways of dealing with Supplemental material published with a paper are not always ideal (eg its existence is not registered in Zotero's paper metadata, it doesn't usually get recognized for download by the Connector, and it is not always obvious when stored under an item). There are probably other examples that need this type of grouped storage too.

A composite or parent item type would perhaps deal with all of these. But that would have to allow citation of any one of the included items.

A composite item might solve the problem, a parent item shows the recent version of the work. The subitems are collapsed by default, and can be expanded on demand. Any item can be cited independently. Technically there is no problem. But more more cases should be take into consideration, such as books, proceedings, or lecture notes as @tim820 noted.