Case when Query in SSRS

I just want to post another new question based on last week's thread:

Visakh16 provided me answer to use "CASE When" to handling different regions (see the Select statement below).

My new question is:  I do need to add a new condition for transaction type = "Billing" after Case when Customer PO In ('12345', '3334444', '23434343'.  These 2 conditions need to be embedded in the region called as"America-Hub".

For the rest of the regions (regions other than America-Hub), I need to filter transaction type = 'Booking".  So How can I combine the above new conditions into One query.

Please help

SELECT other columns...,
CASE WHEN CustomerPO IN ('123456','3343434','2343434')
THEN 'AMERICAS (Hub)'
ELSE RegionFieldHere
END AS Region
FROM ...

Thanks,

Josephine

Josey Tang