use a mysql temporary table in subform

How to create an, on the fly, temporary table in mysql and use it in a Subform?

I have two tables A and B. B has a field “connected” to A’s key. (imagine A=clients and B=clientsproducts)
I have a mainform with table A. mainform has a subform with a query which has fields from table B plus another extra empty (numeric,text, anything will do) field (and a Grid). This query does not allow editions on the extra field. So (I think) I have to create a temporary table which will be updateable and the user will be able to edit the extra field.
How to create the temporary table for use only in that form?

The mainform is presenting clients and the subform is presenting client’s products. Selecting a client, the contents of the subform grid (using client’s id) are changed automatically. I want the user to add some value for every (or some) of client’s products using the grid of subform. The user then clicks the ok button and my other macro collects information of the grid (value and product id).

For the moment I use an ordinary table named CCC which I truncate and refill, every time user opens that form (with all related problems, ex. if another user, in another PC, with another application opens that table will lock, or change data etc.). So it is best to use a TEMPORARY table for that form. Is it possible?