You support someone whose real brain lives in a paper notebook. The shared Trello board is not where she keeps her life. It is where the two of you meet for the few things that have to be seen by both of you. Once you understand that, the board gets a lot easier to use, and you stop wondering why she does not check it more.

What the board is for, and what it is not

Her notebook is for capture and for right-now. It is fast, private, and invisible to you, and that is fine. The board exists only for things that need to cross between you: a task you are handling, something she is waiting on you for, or a piece of reference you both need to find later. If a thing lives only in her head or only on her paper, assume you cannot see it, so anything you need her to act on has to land on the board.

The three lists, and where you fit

Next Action. The single next physical step on something you own or share. Not the whole project, just the next move. If you finish it, move it or archive it.
Waiting On. This is the most useful list for you. When you hand something back to her, or you are blocked waiting on her, put it here with a due date. The due date is what pings her, because her paper never will.
Notes and Reference. Logins, links, decisions, the version of the thing you both keep losing. Put it here so it is searchable instead of buried in a chat thread.

How to add a card she will actually see

Write the next action, not the topic. A card called “newsletter” is invisible to a busy brain. A card called “draft subject line for Thursday send” is a thing she can do.
Put a date on anything time-bound. No date means it will not surface. If it matters by Friday, it gets Friday.
One card, one task. Do not stack six things in one card. Six things means five get forgotten.
Tell her in your normal channel that you added it. A quick “added two cards to Waiting On for you” closes the loop. The board does not replace the heads-up, it holds the detail.

What belongs on her paper, not your board

Her brainstorms, her half-thoughts, her this-week-only reminders, her personal stuff. You do not need to see any of that, and trying to move it onto the board just bloats it until she stops opening it. Keep the board to the handful of shared, durable, dated things. A small board she trusts beats a full board she avoids.

If you want to see how the whole system fits together, send her to the Open Book System, or come see how we support this kind of work at a Hive Session. Start your free 7-day trial.