Major parts of the constitution require as a minimum sixty six percent of the MPs in parliament.
This being the PPP excuse. Well sit down and take Granger's choice now because he is NOT in violation of the constitution. All he needs to say is " I don't like the 18 selected" and he has satisfied the constitution. He is NOT obligated to chose from this if they don't meet his satisfaction.
The Carter arrangement set in place a mechanism where the president would chose from a list provided by the opposition, but this isn't baked into the constitution so isn't illegal.
So continue to make excuses for retaining the Burnham constitution.