problem in the Net Price of PO

in our country 1 EUR = 57800 IRR

length of Net Price in PO = 11 that 2 character for decimal .actually we can use 9 character in net price.

For the foreign purchase we can use the maximum 17000 EUR in net price of po.

we want to create PO for assets. most of them have 250000 EUR value .

if we want to create PO bye the Exchange rate 1 EUR = 57800 IRR , we must use the at least 20 Item in PO for every asset.

I saw the goods receipt of Assets . for the material documents of Asset there aren't FI document.

can we decrease the exchange rate in PO for solve the problem of limitation net price ??.

because Assets don't stores in warehouse . and in the MIRO system use the amount of exchange rate for post the FI document .