Question regarding converting H1B from regular to premium processing

I am on L1 & my wife is on L2, currently at USA.

My new employer has filed my application for H1B petition and I have applied for my spouce's H4 (I539) 

I have received receipt number for H1B petition and H4. Currently it is under regular processing.

I would like to convert in premium processing.

First of all can I conevrt I539 in premium processing?

If yes, do I need to convert both and pay for both application for premium processing?  & what you will reccomend?

See if this helps: