I am trying to build a form that will create new accounts with a unique client number that we can append for each service engagement with that client.  Example:

We engage John Smith as a new client.  We create his account with unique client number 19999.  The first service we provide to John is an estate plan, which for our internal purposes is Matter 1, designated in the system as 19999-1.  

I want to pre-fill the form next time we start a new matter for John Smith, but we may have 25-30 John Smith accounts in our Zoho CRM.  So Last name doesn't work, and account type doesn't work either, because that field is either "Client" or "Not a Client."  The unique record identifier, in our world, is the client number - 19999.  

Is there a way that this custom field can be the Zoho CRM Field for our Form so next time we open a matter under this client number, the assistant types in 19999 and John Smith Account details pre-populate that part of the form?  Otherwise, these dingbats are going to create 100 different clients for the same account.  

If I'm reading the HELP on Zoho Forms correctly, only the Account Name and Account Type are Zoho CRM Fields for that module.  Why is it limited?