How to update item master Data

Hello When i created Item master Data i unchek the setting in General setting in inventory tab "Auto. Add All Wa&rehouses to New Items" after that i import Item Data by DTW after that Item Master Data show blank Wh Info. I allready create 4 No. Warehouse Then i import warehouse info through OITW template now my all master data shows only one Warehouse but now i want item data shows all warehose so how i add all warehose in master Data My WH Code are as NP01,AU01,BW01,PD01 How i update the master data with all above wh code