I'm trying to use your webforms to create a case (or custom module entry) from within another website. We need to link an account to the entry and have tried two solutions:

1. Our preferred solution would be to use the account number instead of the name (because names are more error prone), but this seems to be impossible - whenever I try add a custom lookup field to a module, I can't enter the account number but only the account name (see attached screenshot for configuration)
2. Using the account name seems to prevent us from adding it via a webform: Even though the account name is part of the module, I can't add it to a webform.

Thanks for your quick reply.