using add record to create 2 records -- lookup issue

I have 2 forms, a contact info form (Contacts) and a project inquiry form (Projects).

I am using a stateless form for clients to create both their contact form and project inquiry form.

Projects looks up email addresses from the contacts form for its Partners_Involved field (multi-select, in case I am working with multiple people on the project). This ensures that I have to have full contact info from anyone involved in a project (instead of just letting arbitrary addresses be added).

My stateless for is called "Client_Inquiry" and has the following code on click in a custom button:

insert into Contacts
[
    Added_User = zoho.loginuser
    Admin = "Client"
    Email_Id = input.Email
    First_Name = input.First_Name
    Gender = input.Gender
    Last_Name = input.Last_Name
    Mobile_number = input.Best_Contact_Number
    Role = "Client"
]
insert into Projects
[
    Added_User = zoho.loginuser
    Budget = input.Budget
    Description = input.Comments
    Partners_Involved = input.Email
    Project_Name = "Inquiry from" + input.First_Name + input.Last_Name
    Project_Status = "Open"
    Project_Type = "Inquiry"
    Service_Type = input.Interested_In
]

I think the relationship between fields in "Client_Inquiry" and the other forms should be obvious from the code.

Problem is that on submit I get a lookup error when Projects tries to add the email address. It seems that the new contact record isn't recognized yet, so it doesn't validate in the projects form Partners_Involved form, saying "Error occured while executing on click script. Reference Field 'Partners_Involved' not having the value 'rottentomato@tornado.com'".

What can I do to work around this? I know I could first create a contact record, then forward to a second stateless form to create the project, but the whole point is to prevent 'orphan' contacts or project inquiries by forcing them to be created as a pair. I know I could create 2 buttons ('add contact info' and 'submit') maybe hiding the project fields until the contact is created. That doesn't get around the orphan issue, though, and isn't very elegant. Is there a way to force a re-lookup or submit between the record adds?