Hi Manish, I have had a similar experience in the past. What I found was that the reason Access struggles to link the parent and subforms is because the links are created on the recordsets behind the form(s). Since they are unbound, there is no recordset in the forms themselves to bind.

It has been a while so I don't remember exactly what I did to make it work, but I believe it involved a lot of code to get the form and subform(s) to talk to one another. I think I had to pretty much go through and create procedures for every event in each form to keep everything synced up. For example, manually changing the data in the subforms as the main form changed to a new record, etc.

Or maybe I was just too new at working with Access and VBA at the time and did it the hardest way possible, lol. I'll look around and see if I can find my old files/notes.

    ' Insert new CardNo
    sql = "INSERT INTO casemastert1 (CardNo) VALUES (" & nCardNo & ")"
    CurrentDb.Execute sql, dbFailOnError

    ' Get new CardID which is primary Key
    Me.txtCardID = DMax("CardID", "casemastert1", "CardNo = " & nCardNo)

    Exit Sub
What I done is that, as the CardID is Primary Key, Autonumber, with insert into command I added one field CardNo, and then Call CardID to unbound form, as I have to link the subform with CardID Field.  but with Sub Form I could not

Yeah, you essentially have to have the key field on the main form and each of the subforms somewhere and then dynamically set the recordsources for the subforms manually as needed to respond to events in the main form and then if you update and save any data in the subforms that effect the main form you have to manually refresh that data as well.

Essentially, the forms all start out unbound, but you essentially dynamically binding them through code. Without knowing more about your need to link multiple unbound forms, I don't have any other suggestions. Typically, unbound forms are used for things like menus that don't contain static data, for temporary data, like preparing a list of checks to print from a register, or, the most common I know of is for security and/or to have stricter control of your forms.

In the latter scenario, binding at runtime can be more secure by using VBA as I noted above because if you encrypt your front end by creating an accde file, most users won't know how to decrypt and de-compile the VBA to find the tables.

Manish  Unbound forms don't have records.  Forms need to have records (i.e. be bound) in order to be linked together.  If all your forms are unbound and have no records, they might as well be just any random forms on the screen.  As Donald said, you need to fill your forms with data in the recordsource (i.e. make them bound) before they can be linked.  This can be done either with code at run-time or manually at design time.

Thank you for your kind words, I am already happy with main form i.e. unbound linked with three bound subforms to it. I thought I will learn something new.
Regards.
Manish.

I just use a tempvar that is populated in the Main form in the oncurrent event and use that tempvar in the queries in each subforms to populate them. Don't forget to requery each of the subforms. This will also work with listboxes.