anything provided with the "optional" updates will eventually be provided with the next cumulative.
i always thought more of the early preview versions as a way for users to troubleshoot any possible issue that the next cumulative may cause and save MS the trouble of doing it themselves.
from now on as a safety precaution.. I would install optional updates first on newest pc, since it's SSD only has games and windows - not much to lose if something goes wrong. Then if things go well, would then proceed to install the optional updates on my two older pc.