My original intention was to do an index-card sized naming rules summary of each language of the Eastern Isles. Maybe a 5x7, with a short lexicon on the back. But I'm insane. Upfront work on the languages does pay dividends down the road, though and I'm still not doing full conlangs here... I'm just going further and doing more than I'd previously planned.
The problem is the Dariscene language. It's related to the languages on the adjoining continent, so if I want to have any development there at all, even just naming some major cities and states, I want to know those languages to a similar level. Deriving daughter languages from a parent it's that difficult, but reverse engineering thing the other way is more onerous.I
In addition, Dariscene is itself an ancestor language of the language actually spoken on the isles, the common tongue that I am currently calling "Islander." This is an ideal source for place and personal names that change less quickly than the langiage around them. I'm not sure I need a fully functional common tongue for anything, but I also don't want to wall off any options for the future. Scripts, for example, are something I would love to do at some point, and those should be properly done in the older version of the language unless its adoption is very recent.
So the course of action I would like to take is to develop language families in such a way that I can evolve a small number of ancestor languages into a variety of more recently spoken tongues. The graphic below shows this plan for the human languages: many centuries ago a language I call Proto-Emenic split into a number of branches, two of which are East Emenic and North Emenic. The former eventually evolved into the language of the so-called Dariscene peoples as well as a number of languages spoken on the nearly continent of Emen (the languages listed in italics are actually groups of languages occupying that relational position) as well as the related Valinoi and Shardan groups of languages. The North Emenic branch endures in its descendant, Skörkaga. You can see that Cythric forms a separate branch; if it's related to the tongues descended from Proto-Emeni then the kinship is deep in the remote past. Note that even aside from the groups shown there is plenty of room for more branches.