What was not valid?
Answer the question:
Did the Palestinians declare independence in 1988 ??
The PLO did without consulting the people.
What made the 1988 declaration valid and the 1948 declaration not?
You know the answer to that question so stop asking it.
So you finally admit that the declared independence in 1988.
But with you there is always some bullshit quirk.
Where does it say that they didn't consult the people ? and how is that relevant ?