From what I understand, the final verb determines the reference time of the sentence, but I'm a little confused on how to handle the sequence of verbs with the たりする construction here (particularly after following a stem of another verb):
The way I'm interpreting it, 口をつけ is seen as the verb in focus, while たりもしていた is simply listing any action(s) done alongside with it. But when considering ながら here, it becomes even more confusing how to make sense of the order here. Can someone provide clarification, or possibly correct any misunderstandings I might have. Thank you.