Vitamins wouldn't be any issue as those are available in just about any larger store (from supermarkets to pharmacies to general merchandise stores - even places like $ General and such will carry some) and finding one of those every few weeks would be easy enough.
For the prescriptions the bounce would make sense (maybe keep one older bottle for each medicine and then split the 3 months worth that way, the current supply in the older bottle and the rest in the one it comes in)?
For the second 3 months, it would probably make sense to get all your prescriptions through one of the larger pharmacy chains or other store (Target, Walmart) that have branches everywhere, so that you could simply go to the nearest location (even if that meant taking a couple days off) and get the resupplies there, as they can transfer things from one store to another.
What's really funny is the previous posts about rules that require prescriptions in original labelled bottles when just about any store that has a pharmacy sells those boxes to separate medicines by day or meal. Seems strange that they are allowed to offer those when they obviously go against the rules?