Importing purchases IIF, how to use a sub-account?

Hi, I hope you can help.

When creating a IIF file for importing purchases, I put the account into the ACCNT field. This works if the account is a header account, but if its a sub account, Reckon cant find a match so creates a new account with a type of Bank.

How do I format the IIF file to tell Reckon its a sub-account instead of a header account?

Also is there a way to tell Reckon to NOT create new accounts, new suppliers, etc, if it could not find a matching record, and possible instead log it.

Reckon Accounts Plus 2017

Thanks
Glenn