Storyfag
Perfidious Pole
There is the Ritual of the Bitter Rose, but that just allows multiple-participant diablerie (also sort of amusingly this is not a six-dot but just three-dot and mentioned to be basically not available since only six copies documenting it are suspected to survive outside the Vienna Chantry).
So much usurper wankery, when the real solution is:
1. unearth a torpid Methuselah
2. use xirs vitae to Embrace a brood (size as required by number of interested parties) Cappadocius-style
3. devour the freshly-embraced, confused, low-gen fledglings, lowering your gen considerably
...
4. profit (aka: mutliple beneficiaries who will never have to contend with the ancient mind of the Methuselah trying to wrest control of their bodies from them)
Truly, the minds of lesser clans are incapable of fathoming the simplest, yet elegant, solutions.