Currently, our contacts are set up nicely to recall notes with our clients, whether past or current. However, there is no CRM system for us to keep notes/contact info with other on-site suppliers of our clients. (For example, we are an integrator that does not deal with electric, but we work in synergy with electricians that are on-site during prewire or retrofits. The same applies to general contractors as well, and our coordination and collaboration with them eventually spawns leads for future work.) Is there a way to add a subcategory under "Contacts" to separate paying clients from collaborating partners that we don't sell to but work with during project completion?