Refresh Problem with D2 and Paradox Tables

I am delveloping a Database App with Delphi 2 and I have the following
Problem:

I have several TTables in a TForm called Form1 and the TableType
property of all Tables is ttParadox. There are also 2 TDBGrids in the
Form. In these Grids the Data of two tables (t1 and t2) is displayed.

There is also another form Form2 where I can choose some Actions to do
with the tables of form1 (e.g. delete/insert). This second form is
displayed by a click on a button in form1 (via ShowModal). In form2 I
have placed 2 TTables t3 and t4 and in the Form's Create method I set
their TableName properties so that t1 has the same TableName like t3 and
t2 like t4.
When i'm now inserting a record to t4 and terminate display of Form2,
the changes made to t3 (which is the same as t1) are displayed in the
Grid after a t1.refresh, but the same operation with t4/t2 doesn't work.
I can see the changes in the Database Desktop, but I have no chance to
see them in the Grid.

Who can help me?