Support

ATS is based on the concept that the only people who can interact with a ticket are the user who opened the ticket, the support staff, or people given specific authorisation to view, reply to, or manage the tickets in the category the ticket belongs it.

First please do read the documentation so you have an idea about what I am talking about: https://www.akeeba.com/documentation/ats-for-joomla/deep-dive.html#permissions and https://www.akeeba.com/documentation/ats-for-joomla/nested-categories.html

Therefore, there are two ways you can achieve what you want.

One is, as you said, creating a single user for the entire company. This is the best way to go forward if your support is like ours: organised only by support topic, you provide support to hundreds or thousands of different companies/individuals, and the use case of a single company having multiple users in need of interacting with all of their colleagues' tickets is rare.

The other approach is to create a support system specific to each company you provide support for. This is the best way if you provide support to a relatively small number of companies, and you want the people in each company to be able to reply to each other's tickets. For example, a web agency has a few dozen client companies it works with, and each of its client companies has a few dozen staff which needs to interact with the web agency's support — and with each other's tickets.

For each company you need:

• A Joomla User Group for people in the client company who can submit and interact with each other's tickets, let's call it Company Group.
• A Joomla User Group for people who can provide support to this company's tickets, let's call it Company Support Group.
• A Joomla View Access Level which only contains the Company Group and Company Support Group, let's call it Company Access.
• A category (possibly with topical subcategories) for the company, let's call it Company Category.

You need to edit the Company Category and set the following:

• Access: Company Access
• Ticket Options
  • Auto-select Private: Yes
  • Allowed visibility: Private Tickets
• Permissions: Company Group
  • Create: Allowed
  • Reply to Any Ticket: Allowed
  • Edit state: Allowed (ONLY if you want them to be able to re-open their own tickets!)
  • Create private: Allowed
  • Read private: Allowed
  • Create attachment: Allowed
  • Download any attachment: Allowed
  • Delete any attachment: Allowed
  • All other permissions: Inherited
• Permissions: Company Support Group
  • Support Staff: Allowed
  • All other permissions: Inherited

You do not need to change the permissions in child categories. You do need to change the Access, Auto-select Private, and Allowed Visibility in child categories.

The users of your company (the company's staff) are added to the Company Group.

The people who provide support to this company are added to the Company Support Group.

Yes, your use case seems to align far better with the second option.