I believe dual/single weapon variants and fighters and missile weapons using the same payload should be related in codex — this would help give players a means to compare similar options when trading and to build a better understanding of the relation between mount size/OP cost and weapon statistics.
A decision on this also sets precedent for best-practices concerning modded codex entries.

There's also an argument to be made for related entries between different sizes of non-missile weapons, at least for world-building purposes (i.e. mortars, autocannons, needlers), but the utility of statistical comparison is less strictly relevant for these and more subjective case-by-case.
suggestion aside, thank you for the codex update! it's been a wonderfully considered feature and a joy to navigate.