Create a cascade between cards on different lists (not checklists)

[Megan Hyndman]

I'm not savvy on sophisticated processes, but have used automations successfully in the past. I have several lists that are connected in real life via stages, in that one set of tasks from List 2 can't begin in real life until first set of tasks from List 1 is completed - so what I have is "To Do" labels on tasks that are first-up, with the hope of when that task is completed, the "To Do" label gets popped on the first card of List 2, whatever that card may be. As an example:

-List 1 is Drafting and has card named "First Draft" with label "To Do"

-automation is currently set up that when that card is checked complete, it moves to list "Completed" and the label is removed

-I would then like the first card on List 2 (titled Marketing, with several cards labeled "Stage 1") to now get the label "To Do." 

I don't care whether I need to automate via the card movement ("when card is moved from Drafting, apply To Do label to top of Marketing") or through labels ("when To Do label is removed, apply To Do label to top of Marketing" or "when To Do label is removed, add To Do label to card labeled "Stage 1"). I'd rather just have the top card on Marketing get the To Do, but would be ok with all of the Stage 1's getting the To Do....but I can't seem to find any way to automate this without having to physically go in and pre-link all the cards in the attachments, or link all the cards in Marketing, not just the Stage 1 labels. The "find card" option seems quite limited. Any help?