The problem of identity through change asks how one individual can be both distinct from and identical with itself at different times. (The notion of identity through change looks like a contradiction in terms.) It can be solved by identifying enduring objects' natures with first-order bundles that are bundled with further tropes at different times.
There is a distinction between natures and accidents. A being a's nature is an instance of whatever every being of a's kind has that it can't gain or lose, and that makes it unique from beings of every other kind; its accidents are property-tropes that it might not have had. A young ass has the same nature as the lame old donkey it becomes; it, however, has different accidents.
There is also a distinction between first-order and second-order bundles. A first-order bundle is a system of dependent tropes combined into an independent substance; a second-order bundle is a system of dependent tropes combined with a first-order bundle into an independent substance. The system of dependent tropes combined into a donkey's nature is a first-order bundle; the system of dependent tropes combined with that nature into a donkey-with-all-its-accidents is a second-order bundle. I contend that all natures are first-order bundles and all natures-with-accidents second-order bundles.
These distinctions dissolve the problem of identity through change. The young ass, for instance, is a numerically distinct second-order bundle that has one and the same first-order nature as the old donkey it becomes. It and its counterpart are, in other words, the exact same (first-order) donkey with different accidents at different times.