Default Value

=Forms!CustomerF!CustomerID

I'd also recommend Search 2.0

https://599cd.com/blog/display-article.asp?ID=2079

Peter
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What you are wanting to accomplish is very much like entering in a new order for a customer that Richard shows in the Invoicing TechHelp.  Especially  the extended cut.
Keep in mind that the default value is only good for the customer you are on.  You need to open the form, make the change or addition, and close the form for that customer. This is to prevent un-linked records being created.
If you want to be able to open the secondary form and be able to freely enter data for any customer a different approach would have to be utilized.  See the  Search Form 2.0    Dan mentioned above.

Hi Scott, tnx I will take a look at the invoicing Video. My goal is to be able to enter additional information on a secondary form for a specific customer, so my main form doesn't get too full with subforms.  And apologies for the rule violation, I will upload the image separately.

Peter - no  problem on the image link.  Just safety and it also prevents a bunch of broken posts because people remove their images.

Anyway - long story short if in your EmailContinuousF you set the default value if the CustomerID to be that of the opening form that should do the trick.  You will need to use the Forms!FormName notation to "carry over" the ID

Like this:  =[Forms]![CustomerF]![CustomerID]

If you are not familiar with that a good video to watch is the Value From a Form

Hi Scott, I did use =[Forms]![CustomerF]![CustomerID] (see extra screenshot) but that still doesn't fill in the customer ID when I add an email adres as you can see on the first screenshot.

Peter - You need to use it in the properties on the EmailContinuousF form for CustomerID.

Hi Scott, this makes no difference.  The first record that shows when I open the form always has the CustomerID, whether I use [forms]![klantenf]![klantid] or not. But when  I want to add a record for that customer, the  ID remains blank.

Peter,

What concerns me is the #### for new records in your Email form. Make sure you are using the correct ID (from the Email table).
To be honest, I don't understand why you need the query. Can't you just make the Control Source of the form EmailT?

Solved! I switched from query back to the email table AND changed the field name for the client ID in the EmailT  from eKlantID to (just) KlantID, like in my KlantenT. That somehow caused the problem.  With subforms It can be useful to not use identical ID field names, but in this case it was the other way round. Tnx for your help!

Peter, you can still use a subform, but make it visible or invisible when needed, so it doesn't always take up screen space.  That button you made to open another form, use it to set the subform's visibility instead.  That way the CustomerID is always linked, and you avoid all this hassle.

hi Rabid, that's a creative workaround! But you would need two buttons then, one to make it visible and one to make it invisible.

You could do something like this and only have one button.

Private Sub btnHideEmails_Click()

    If btnHideEmails.Caption = "Hide" Then
        EmailSubF.Visible = False
        btnHideEmails.Caption = "Show"
    Else
        EmailSubF.Visible = True
        btnHideEmails.Caption = "Hide"
    End If
    
End Sub

Hi Peter, you only need one button to "toggle" the visibility, and only one line of VBA:

Private Sub MyButton_Click()
   Me!MySubform.Visible = Not Me!MySubform.Visible
End Sub

Ok, I understand Kevin's code, but Rabid's line is a bit of a mystery to me...., but I tried it and it does work! :)

Rabids line basically says make the visible property whatever is NOT the current visible property. So if the current visible property is set to false, then your setting the visibility to NOT false (true), works because it's a boolean property (true/false)