Will it be more effective to make the request: “Source Creator, deflect all outside manipulation of the upcoming mass meditation in service to humanity?” Or, can both be done?

This, in fact, will do much more towards the goal you seek because it is asking the Divine directly, to counteract an influence from interlopers who are not invited and have no good reason to be here manipulating humans to begin with, and as such, are not entitled to as much power to carry out their dark deeds when opposed by the divine human in some form. Even a single requester will have the standing to enlist considerable divine help with such an enterprise and that is because they have more weight, even though outnumbered by extraterrestrials. So this will be at least a halfway measure to prevent further programming and subjugation of those who choose to participate and then make themselves known to the Extraterrestrial Alliance because of their participation, self-identifying as seekers, and therefore, a potential liability to the dark plans of the Extraterrestrial Alliance, being humans who are still not fully subjugated by virtue of displaying interest in a group meditation. For maximum overall benefit, it would be good to do both things to deflect and constrain any surreptitious influence by the Extraterrestrial Alliance of participant humans and also to use the desire of all present to add divine help to the extent possible on behalf of each believer to channel their energy into dealing with the Extraterrestrial Alliance—the true cause of the Earth’s difficulty at this time.