How do I create a vba function to add a row in MS Access?

Something like this:

    Dim RS As DAO.Recordset
    Dim Count As Integer           
    
    Set RS = CurrentDb.OpenRecordset("Select Top 1 * from YourTable")
    
    For Count = 0 To Nz(Me!ComboCountOfNewRecords.Value, 0)
        RS.AddNew
            RS!SomeField.Value = SomeValue
            RS!OtherField.Value = SomeOtherValue
            ' Etc.
        RS.Update
    Next
    RS.Close

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I would like to create a vba expression to add and remove rows by using a combo box containing a value list of 1-40. For example, if I select 3 from the value list, it will create 3 rows. If I put the list to null then 0 rows or hidden. The row consist of 3 combo boxes, and 5 text boxes. How do I create a vba function for such thing?

Please, elaborate.
And keep in mind that a relational database does not work like a spreadsheet, adding a row can be done with a reacordset (as Gustav suggested) or an INSERT query, but providing no value make little to no sens.

I attached a File to show yoy what I would like to do. The file only works for text boxes, and I am not able to change the record source to design one. I also need to convert 3 of the text boxes to combo. When I do that it misses up the table.
FakeTable---v2--1-.accdb

So you are creating controls (textboxes), not records. That was not easy to guess.

The easy method is to create the form having the maximum count of rows and columns, and then hide them all.
Then, after having selected the counts, unhide the rows and columns as requested.
Much simpler and faster, and no trouble positioning and sizing the textboxes.

Hmm, dynamic GUI within ms Access can be troublesome, as it wasn't designed for that purpose.
Toggling control's visibility is the best you can do (so your mdlControl module is just a "No, no no !!")

Side note:
- Your number of rows combo-box should start at 0 (a table without rows make sens).
- Your number of columns combo-box should start at 1 (a table without rows make no sens).
- Both your combo-box should provide a default value (null as a number of rows or columns make no sens).
- Your FormatTable function break the SRP, move all the cosmetic stuffs in separate functions.
- You don't need to requery a form if there is no change to data.
- Don't think the "dummy" control is needed at all.
- Instead of a function hiding everything plus another making controls visible, write one that set controls visibility directly (more efficient).

Private Sub SetColumnsVisibility(ByVal numberOfColumns As Integer)
    Dim ctl As Access.Control
    For Each ctl In Me.Controls
        If (Mid(ctl.Name, 4) <= numberOfColumns) Then
            ctl.Visible = True
        Else
            ctl.Visible = False
        End If
    Next
End Sub

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Attached is your updated database, all cosmetic stuffs are commented out, I leave that up to you.
FakeTable---v2--1-.accdb

Joseph,
We have no idea what you are trying to do.  YOU decided the solution that you want US to implement for you.  What you have determined is the "solution" is wrong on many levels.  You should remove your spreadsheet hat and spend some time learning relational database design.

Of course if you explained what problem you are trying to solve rather than what you think the solution should be, we would be in a better position to help you.

Well there are a lot of thing that are doable but probably we need some more info on what and why you try to accomplish.
Lets assume that you simply want to create controls...then Application.CreateControl is the way you do it...you give the form you want to create the control...size,position parameters ...later name and that't it...
But more important is the functionality you wish to achieve...so maybe there are other easier ways to achieve what you want.