custom duty_urgent

Hi experts,

I need to deal with custom duties for foreign vendors.

created PO with custom duties

Now my doubt is Whether GR is to be posted first or Custom invoice

Becoz I tried to post custom invoice prior to GR

chosen 2.planned delivery costs in MIRO -po reference screen

But I couldn't enter the quantity as the filed is disable mode

Could some one guide me to resolve the issue

It's urgent

Thanks in advance.