Via skillful reuse of View and other code modules between suites, each test suite can be treated as an independent target without increasing maintenance unacceptably. Ideally, only abstract fixture setup and test flow is expressed in the test function, with all other maintainable aspects in reusable modules. So long as groups agree to maintain interfaces and promised behavior of shared module code, they can each work freely at any level of communication.
Of course, each group should have an opinion on coverage for either suite, and can (and should) help expand each suiteboth suites, but single point of ownership allows decisions to be made quickly as appropriate for each set of primary stakeholders.
= Timeline =