Yes, but I fear you're missing the true meaning of APPEND.
APPEND doesn't simply add data to a field, it adds a whole new record. You have 5 records in TableA and run an APPEND on it and afterward you would have more than 5 records in TableA.
Last, one of the fundamentals of normalized database is that you store discrete pieces of data discretely. That is, you don't jam together individual pieces of data into one field--you give each its own. Another funamental is that you don't move data around. If its in one place, you don't move it to another, you simply reference that place it is in.
So, why do you need to break the fundamental way your database should operate? What will this APPEND do for you?