子窗体的联接

两个子窗体怎么实现下列功能：  （两个子窗体用不同的源，窗体2字段1的值取等于窗体1字段1的值，但不重复，入下图所示，窗体2的数据随窗体1的改变而改变）

      子窗体1                  子窗体2                             子窗体1                  子窗体2          

     字段1    字段2          字段1     字段2                    字段1      字段2         字段1      字段2

        A         12                  A         11                     A              2              A             33

        A         22                  B         22                     A              5              B              22

        B         13                  C         12                      B              6              C              25

        C         15                                                      B              8              D              23

        C         16                                                      B               3

                                                                            C               5

                                                                            C               3

                                                                            D               9