You can append from a table as long as it's not used exclusively. If table is opened exclusevly elsewhere, you cannot access it at all.
You can use INSERT INTO...SELECT FROM to copy records from one table into another.

>I am doing:

>use mytable
>append from other_table

>
>However if other_table is in use, append will fail
>
>Is there a way for appending from an table in use,
>even that I use other commands along or instead of "append"
>
>Moises