>I have this grid with the AllowAddNew prop set to .f.. By means of a button I set AllowAddNew to .t., Append blank and add the first field which is a memory variable. After the record is completed, if the user presses the down arrow, a new record is added, wether you want it or not. What would be correct way of avoid adding a new record if it is not wanted, or delete the record by simply pressing the up arrow, for example, if a new record is not wanted?

Leave AllowAddNew off, because even with it off, you can still APPEND BLANK to the table. AllowAddNew is to let you automatically Add a new record if you press the down key on the last record, which it sounds like you don't want.