You can enter "Applied For" or "NRA" in that space, but would need to also complete Form W-7 for him to get an ITIN.
See IRS 2019 Form W-7 Instructions with when and where to apply on page 5
For an overview of the process, click this link: Who needs an ITIN or Individual Tax Identification Number
For all the rules, see IRS Publicaiton 519 page 7. Please check out the details when a Nonresident Alien can be treated as a Resident Alien and what must be done the first year of this election.
For your daughter, IRS US CItizens living abroad filing requirements
