Persisting a component at the bottom of formSheet across different sizes

[2Senn]

I am wondering if there is a way to keep a button for example persisted at the bottom of a formSheet presentation screen. I currently have a structure where there is a heading, a list, and then a button that should be absolutely positioned at the bottom. This is not an issue on a normal screen but when using formSheet presentation it does not seem to work. Mainly because the parent never flexes or takes up the full height of the sheet for some reason.