Mapping of Item no. when Item no. is different in the two companies.

If the Item no. in your Intercompany companies aren't the same, it is recommended to use Common Item no. for mapping Item numbers. 

Item card 

Give your Item a No in Common Item no. in both companies.  

Partner card setup 

On The IC Partner in SALES COMPANY, “Outbound Purch. Item No. Type” should be set to “Common Item No.”.

On The IC Partner in SUPPLY COMPANY, “Outbound Sales Item No. Type” should be set to “Common Item No.”.