hi
try this
[EventSubscriber(ObjectType::Table, 37, 'OnAfterInsertEvent', '', false, false)]
local procedure SetYpurField(var Rec: Record "Sales Line")
var
SalesLine: record "Sales Line";
begin
SalesLine.Reset();
SalesLine.SetRange("Document Type",rec."Document Type");
SalesLine.SetRange("Document No.",rec."Document No.");
SalesLine.SetFilter("Line No.",'<>%1',Rec."Line No.");
if SalesLine.FindFirst() then
begin
rec.YOURFIELD:=SalesLine.YOURFIELD
rec.Modify();
end;
end;
check my answer if it helped you, thanks
DAniele