trying to figure out if my husband and I can file listing our two daughters on the return. our youngest doesn't have a ssn yet, so it seems we just can't list her at all?
If the child does not have SSN then they cannot be entered on the tax return as a dependent.
Why does not a 3 year old have a SSN? Have you applied for a SSN?
You are correct, you can't list her as a dependent unless she has a social security number. You can use this link to apply for a social security number.
And....you might want to get an extension and file later if you are waiting for the SSN. The form to get an extension becomes available in March, and you could get an extension that lets you wait until mid-October to file. If you file now without the child's SSN, you are not allowed to go back later and add her SSN to claim her.