Link one workbook to another workbook?

I have a Master Log in an Excel workbook with all my vendors, It has (date,Quote#,ect...) I also have an Excel workbook that contains the format PO Request, It also has (date, Quote#, Part#, ect...) so I need to get the information from the PO Request form into the Master Log. I've tried Macros it's work as far as pasting all the information into the Master Log, however it will not add a a line it will enter the information on the same line over again, How can I do this without having to copy and paste everything, is there a more efficient way for this process? Any information would help. Thanks!