since you did not mentioned what are the selection criteria for selection of TR i hope on the selection screen u will find
based on selection criteria you select No of TR from LTBK along with TR Number & TR Line item number TBPOS
Find the TANUM from LTAK against the LTBK-TR Number (this will ensure that you are picking all the TRANSFER order against the TR number)
Once the LTAK-TANUM is obtained then link this with LTAP-TANUM and TBPOS(which is TR line item number)
Hope it is clear now