Timeline is a fantastic feature of BrightManager yet somewhat limited in function for a multi-tech stack enviornment.
Could it be considered to provide functionality to allow updates to a client Timeline (adding a note), by the use of an API.
This could be provided via the Zapier integration in the first instance (for expediency), with the ability to search a client record using either the Client ID, Client Name or custom field (such as internal reference) for adding notes to the Timeline.
Optionally, to provide categorisation to the note would provide for future filtering.