dbengine(0)(0).TableDefs("AnyLinkedTableName").Connect
Will give you the full path and name of the database where the linked table is.
However, the connect string contains other info than just the path and file name. You will have to do some string processing to eliminate that. Ex:
From the On_Open event:
Dim strConnect as String
strConnect = Mid(dbEngine(0)(0).TableDefs("Tbl_Contractos_DadosGenerales").Connect, Len(";DATABASE=") + 1)
Me.txtBackEndPathAndNAme = strConnect
Alex