Hello,
You should use F-53 to clear your DP request by entering special G/L used during F-47 and create down payment. Counter entry would be bank G/L. When you do this DP request would be cleared and DP document would be created as open item.
Alternative is to use F110 to convert DP request to DP.
F-48 is for directly posting down payment. No DP request is needed here.
Please note that DP request is noted item and DP is special G/L item
Hope it is clear.
Thanks,
V V