Instance-specific partials exist as properties of ractive.partials.

Ordinarily, these are declared as an initialisation option. However it is possible, should you need to, to add or replace these partials (obviously, doing so wouldn't affect partials that were already rendered):

Where necessary, partials will be parsed at the point of use, and stored as parsed partials thereafter.

If Ractive encounters a partial mustache, e.g. {{>rickroll}}, it will look for instance-specific partials before looking in Ractive.partials.