Purchase order as a control

Question

can anyone tell me all those t.codes from where i can make purchase order a required field.
i want to have control through purchase order.
is it possible to have control if i make sorting key 014 in vendor recon account. and fsg g067 contains purchase order a required field. plus bank fsg g005 also contains purchase order as compulsory field.
our problem is that whenever we see any vendors account open items , we are not able to see purchase order no in purchasing document. column.
what i know is that using ob41 i can make po as required field for posting key 39 used for adv pmnt request, plus make po as sorting key plus, fsg g067 containd po required field.
can any one help on this?

Answer 1

we prepare pr then po then cit captures part1 then grn then cit captures part2 then miro is done.
ques 1
problem is that if we have po valuing rs 100000 and corp office makes pmnt rs 100000 then if allowed plant also can do the pmnt and sap system will not stop as when any one looks into the account of vendor whom payment is being done then po no is no reflected in purchasing document no. column
quest 2
how can we see the po no in the purch document column when we see any vendor account using t.code fbl1n.
question
plus how can we make it possible that total pmnt doesnot exceed total po value no matter how many bills are received wrt to one po and no matter what our pmnt terms are.