FYI: Note that that is not a “lookup field”, that is a “linked record” field.

Also, you just asked this exact same question yesterday in this post.

The answer I gave you yesterday remains the same as it does today:

Adding new linked records within a form isn’t available in Airtable, but you can email the support team to ask them to add that as a feature request, and you can also add that as a feature request to the ongoing list of Airtable feature requests in this thread.

However, as I mentioned yesterday in your previous post, you have 2 other ways of doing this:

1. You can place text on that form which gives them a link to click on, which will open up a new form in a new tab to enter new linked records.

2. You can use Fillout, which is the world’s most advanced form tool for Airtable. It gives you the feature you’re looking for, along with hundreds of other advanced Airtable-specific features that Airtable’s native forms don’t offer. I just gave a demo of Fillout on this episode of the BuiltOnAir podcast.

You may also be able to do this in a portal tool like Noloco, but I haven’t checked.

p.s. If you have a budget for your project and you’d like to hire an expert Airtable consultant to help you with any of this, please feel free to contact me through my website: Airtable consulting — ScottWorld 

There is also a clunky workaround for this — but I do not necessarily recommend this method because of all the clutter it adds.

You can add a fake linked record called “CREATE NEW RECORD” or something like that. When the user chooses that item, you can conditionally show a whole bunch of other temporary fields on your form for the user to fill out. Of course, when the form is submitted, all the data will go into the same table, so you would then use an automation to copy & paste all of the values from the temporary fields in the first table to the real fields in the other table.