Hi @mcarleton
Yes you can try this way
I have developed a demo flow in power automate



Let me explain what i have done step by step
Here my bot will triggers when mail with subject line Training Information arrives in outlook
Steps
1. Trigger to run event when mail arrives is added in the flow
2. Now it will remove the unwanted text from subject, for example if the person is replying to same mail, there would be RE text along with the subject line, this s done using compose function named as Subject.
3. List Task is to list all the task in a specific group in planner
4. From values of the output of list tasks, add the title field from json to an array [ Plan title would be the title field ]
5. Use contains to check whether that array contains the subject name [ assuming that subject name would be plan title]
6. If it is true, then update the task [ I haven't added the sequence, you can add it]
If it is false, create the task
This is how you can do
Let me know if you have any questions 🙂
Thanks & Regards,
Nived N