Welcome back! If you indeed have a master-child page, it will resemble this setup:
Just right click in the button-bar, select Add button => Action, that will make the Action button get created.
Next, right click the Action button, and select ‘edit on click action’, and select ‘call a microflow' and click button 'new'. Give it a name and click ok. Now a microflow has been created. The beauty is: it has two input parameters, both the master object and the child object.
Hi Rob,
This is indeed now part of the platform works. If you create a microflow button and have the parent as an input parameter, the platform will identify the correct object to send to your flow. See the below screenshot: