Nested Fragments talking to their parent fragment via scoped Activity ViewModel

file.kt

class ProfileActivityViewModel : ViewModel() {
    val tabCounterLiveData = MutableLiveData<Pair<String, Long>>()
}

class ProfileActivity : AppCompatActivity() {
    @Inject lateinit var viewModelFactory: ViewModelProvider.Factory
    private val viewModel by lazy { ViewModelProviders.of(this, viewModelFactory).get(ProfileActivityViewModel::class.java) }
}

class ParentFragment : Fragment() {
    @Inject lateinit var viewModelFactory: ViewModelProvider.Factory
    private val viewModel by lazy { ViewModelProviders.of(this, viewModelFactory).get(ProfileViewModel::class.java) }
    private val activityViewModel by lazy { ViewModelProviders.of(requireActivity(), viewModelFactory).get(ProfileActivityViewModel::class.java) }


    private fun observeChanges() {
        activityViewModel.tabCounterLiveData.observeNotNull(this) {

        }
    }
}

class ChildFragmentOne : Fragment() {
    @Inject lateinit var viewModelFactory: ViewModelProvider.Factory
    private val viewModel by lazy { ViewModelProviders.of(this, viewModelFactory).get(ChildOneFragmentViewModel::class.java) }
    private val activityViewModel by lazy { ViewModelProviders.of(requireActivity(), viewModelFactory).get(ProfileActivityViewModel::class.java) }

    private fun sendTabCount() {
        activityViewModel.tabCounterLiveData.postValue(Pair("ChildFragmentOne", 100))
    }
}

class ChildFragmentTwo : Fragment() {
    @Inject lateinit var viewModelFactory: ViewModelProvider.Factory
    private val viewModel by lazy { ViewModelProviders.of(this, viewModelFactory).get(ChildTwoFragmentViewModel::class.java) }
    private val activityViewModel by lazy { ViewModelProviders.of(requireActivity(), viewModelFactory).get(ProfileActivityViewModel::class.java) }

    private fun sendTabCount() {
        activityViewModel.tabCounterLiveData.postValue(Pair("ChildFragmentTwo", 100))
    }
}