We are trying to create a custom form to be used as a Project Ticket. The ticket custom fields on has 9 custom text types to choose from and an attachment is not one of them. We do know that the ticket itself has an attachment option, but it's not mandatory AND we only want it mandatory if a contract has already been obtained. So we are are ultimately looking for a custom ticket to do 2 things: When users selects that there is already a contract in progress, that a box appears telling them they must attach a contract.
Best way to attempt this is via action rule.
You can use this to edit a ticket, which can include a custom field telling them what you need it to say. Not that sure about popup boxes and stuff like that. But you can send an email stating that they are required to attach a contract.