I'm looking to send a form to an existing customers which will enable them to register up to five members of their staff for some training. 

There is already a CRM Deal, Account and Contact.  This form needs to be sent to the customer so that they can complete it, enabling the collection of details for their trainees.

My question is: Can you have multiple contacts on the same form?  So there is a section for "Trainee 1", "Trainee 2", "Trainee 3" etc. Each with their name, job title, email and phone to fill in or does the form have to be submitted five times to capture five different people's details to create these as contacts under the same account in CRM?

How would I relate the account to this?  The CRM -> Forms integration is setup but unlike a Mail Merge, how does the form know which account the contacts submitted relate to?

I understand how to create forms that create accounts and contacts using a lookup field but I don't want the customer to pick their organisation from a lookup.   Multiple accounts might be access the form at the same time, so somehow the form needs to recognise the initial recipient, know the account it's associated with and then add the five new contact to their associated account.

Any ideas how this can be achieved? 

I intend for the customer to access the form from a CRM email template which will have a "Click here to register" button on it.  Sent from CRM.