First add a new property as array inthe main form(containing the grid) named RunnedEdit
In double click event of the grid:

 DECLARE thisform.RunnedEdit[ALEN(RunnedEdit,1)+1]
 thisform.RunnedEdit[ALEN(RunnedEdit,1)+1] = SYS(2015)
 thisform.AddProperty(thisform.RunnedEdit[ALEN(RunnedEdit,1)+1])
 c_name = "thisform."+thisform.RunnedEdit[ALEN(RunnedEdit,1)+1]
 DO FORM EditMemo NAME &c_name LINKED WITH ...

In AfterRowColChange of the grid:

 FOR i = 1 TO ALEN(thisform.RunnedEdit,1)
     c_name = "thisform."+thisform.RunnedEdit[i]
     IF TYPE(c_name) == "O" .AND. .NOT. ISNULL(&c_name)
        &c_name..Refresh() && or &c_name..EditBox1.refresh()
     ENDIF
 NEXT

If you are using VFP 8 you can use the collection class to do this (not the array). Of cource You can ADEL() the RunnedEdit array after the user close the EDITMEMO form or in double-click event check for existing of the form before decalre new elemnt of the array.