There's no reason you can't convert 3 x V6 into 360 using a software drop, but this will need an engineer visit. The underlying reasons why 2 x V6 can be converted using the "self-serve" methods but 3 can't, have never been entirely clear - but this rule has been consistent.
I have no idea why you're being advised to change package in order to do this migration. Package changes & equipment changes are completely separate.
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