I am sorry it does not work that way. You need to refer it to your Islamic scholar for details.
Who told you that he needs permission ? Why does he need to tell his first wife ? What kind of satisfaction his first wife will get out of this information. Dill he jalay ga baycharee ka.
Magar mairee toh darheee hee nahi. Tinka ataknay ka sawal he nahi paida hota. 
Why does she need to know. It will give her grief only
Even if the economical sitution permits it. The kind of women men need to deal as wives now a days makes it impossible to even think of another wife. 