With software as a service (SaaS), businesses often build applications for multiple customers, each with their own users, to create a business-to-business-to-consumer (B2B2C) or business-to-business-to-employee (B2B2E) model. In B2B2U models, the SaaS business creates an application sold to intermediate businesses that then provide access to end users. These applications introduce complexity around customer and user modeling, requiring balance between meeting customer requirements and delivering value to ultimate users. Examples of B2B2U platforms include private-labeled job boards, diagramming software for employees, and LLM chatbots for enterprises. The relevant entities in these systems are the SaaS business, intermediate businesses, and end users. B2B2C platforms focus on consumers paying or potentially paying the intermediate business, while B2B2E models target employees or contractors of intermediate businesses. Both types require balancing technical flexibility, security, scalability, customization capabilities, and user-centric design. However, B2B2C platforms prioritize acquisition, conversion, and retention features, whereas B2B2E systems focus on enterprise control and access management. SaaS providers must develop flexible applications that accommodate varied business requirements, complex authentication protocols, and bespoke security needs while balancing security, performance, and user experience across multiple organizational boundaries.