I apologize for the click bait title, but that's really my question.
35 USC § 102(a)(2) provides:
A person shall be entitled to a patent unless—
(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claiming priority is valid if one inventor is the same (plus a few more things) according to the relevant paragraph.
If the priority is not valid for any claim x because the claim is not sustained by the old description, this could mean a valid priority for the patent application and the priority document being prior art for the obviousness of claim x.
Wouldn't that make claiming with a different inventor (and one that's the same) a mad gamble?
Or to put it into practical terms, shouldn't an additional inventor for an application that's supposed to claim priority reiterate if their contribution was actually enough to merit inventorship because it might kill claim x, even if they only contributed to claim y?