I already showed you how to link the files in a query in my previous post.
Its is true that I am not using Dbase IV, so I cannot be 100% sure that the language functions that I showed are in that 'flavor' of the language, but UPPER() and LEFT() are supported in most, if not all, languages that incorporate SQL queries.
LEFT(UPPER(Table3.FINVNO),6) = LEFT(UPPER(Table2.FINVNO),6)
That links Table2 to Table3 using the LEFT 6 characters of the FINVNO field
LEFT(UPPER(Table1.FINVNO),6) = LEFT(UPPER(Table2.FINVNO),6)
Links Table2 to Table1 using the LEFT 6 characters of the FINVNO field
Therefore using both of those as shown in my sample code would link both Table1 & Table3 to Table2
So what is it SPECIFICALLY that you do not understand?