Why reduce polls-time Govt size if its head does not change?

A news items has been published in a daily that the ruling party is going to form an all-party interim government with 10 members headed by Sheikh Hasina. We cannot find any justification for forming an interim government by keeping incumbent Prime Minister at its head.
What is the need to shorten the size of the Cabinet to 10 if it is headed by the sitting Prime Minister?
We all know that problem will be resolved immediately if it is declared that the head of interim government will be chosen by all parties.
Sheuly Haque
Tarash
Sirajgonj