How do I make a second text field within a datacard required or fix the required code on the primary combobox?

[Future_Vision]

Above is what I am working with. If the Source combobox includes '3rd' then the datacard below it shows. That datacard also becomes required using this code.

If("3rd" in Source_CB.Selected.'Source (cr9c7_name)', true, false)

Now, if  the "** Add a 3rd Party **" option is selected the "Add 3rd Party" text box appears. You enter a value and click "Add" and the new value is populated in the 3rd Party combobox. That all works great except when I come to validation. First, if you choose a "Source" and don't do anything to account for the "** Add a 3rd Party **" option the form validates and is submitted with the 3rd party being "** Add a 3rd Party **". I don't want that to happen. What I was originally thinking was that there was some logic that if "Source" contained '3rd' AND the "3rd Party" combobox had a value of  "** Add a 3rd Party **" then the form would not validate. I couldn't get that to work. I tried something like this:

If("3rd" in Source_CB.Selected.'Source (cr9c7_name)' && '3rdParty_CB'.Selected.'Third Party (cr9c7_thirdparty)' =  "** Add 3rd Party **", true, false)

Then I was thinking what if I can make the "Add 3rd Party" text box required when "** Add a 3rd Party **" is selected that might be the answer to this form validation issue. No such luck putting required on that second text box within a datacard.

I'm sure I am overlooking something simple here. Ultimately, I want to make the form invalid if the text in the "3rd Party" combobox is "** Add 3rd Party **"

[Drrickryp]

@Future_Vision 

To really understand how a form works, you only need to know two things.  First, the default property of the control inside the card and second, the Update property of the card.  Everything else in the card is pretty much superfluous. 

The Default property of the control is usually set according to the Parent.Default for the field of the card.   

The Update property of the card determines what value is saved for that field. If you are saving some combination of values from controls in the card, this is where you would write the formula for that. 

[Future_Vision]

@Drrickryp I'm not sure I completely follow. 'Source' is it's own card and "3rd Party" is its own card. I just need the form to be unsubmittable if "Source" contains "3rd" AND "** Add a 3rd Party **" is selected for "3rd Party"

[Future_Vision]

Just to be clear. The "Add 3rd Party" field only patches a new value to the dataset and adds the value to a variable when "Add" is clicked. The "3rd Party" combobox refreshes with this new variable value selected. So this brings me back to the form being valid and ready for submission only if the value in the "3rd Party" field is not blank or contains "** Add 3rd Party **".