Amendments can add to the text or change it. It shouldn't be changed lightly, since each clause affects others
This section actually amends the text by making exceptions
to Article I, Section 2 and to Amendment XVII,
to provide for filling multiple vacancies in either House when it falls below quorum,
as long as special elections are held promptly or elections are less than three months away.
Because the individual amendments are similar in purpose
and affect the same Constitutional provisions
in the same way in the same clause
the three are presented here as a group.
Article I, Section 2:
"When vacancies happen in the Representation from any State,
the Executive Authority thereof shall issue Writs of Election to fill such Vacancies."
"When vacancies happen in the representation of any State in the Senate,
the executive authority of such state shall issue writs of election to fill such vacancies: Provided,
That the legislature of any State may empower the executive thereof to make temporary appointments
until the people fill the vacancies by election as the legislature may direct."
Amendment XXVIII, (proposed), Section 4:
"But when less than three months remain in the term
or when the President declares a state of emergency,
a State's legislature may empower its executive to make temporary appointments
before issuing writs of election;"
"[...] when that office is vacant, that legislature will have power to make temporary appointments
before issuing writs of election."
"when a State's legislature also falls below possible quorum,
its executive will have power to make temporary appointments to Congress before issuing writs of election, [...]"
This section amends the text of Article I, Section 2, which makes no exception,
by allowing state executives to make temporary appointments to the House of Representatives
under certain circumstances when making quorum becomes impossible.
This section also amends the text of both Article I and Amendment XVII, neither of which makes any exception,
by empowering Governors to make temporary quorum appointments if the state legislature also falls below quorum
and is unable to empower its governor to do so,
or to empower a state legislature to make temporary quorum appointments
if there is no executive authority in the state to do so.
The purpose of Amendment XVII was to remove state power over the Senate, restoring it to the people.
But its original text empowers states to make temporary appointments when needed,
so State Powers in Emergencies doesn’t add much
and is itself checked by the public’s right to petition it if writs don’t issue.
In each case, the extension fits the original clause logically. No other text is disturbed.