I mis-spoke re: Allocate ... it is a function available for each Feature in the PORTFOLIO ITEMS list (on the leftside of the Capacity Planning page)
When 'Allocate' is selected, we see yet another 'Estimate' field ...
This Estimate field appears to populate the Group Estimate field ... I assume that you use it to populate the 'Group Estimate' field, again with Story Point units. Is that correct? Thanks again for taking time to explain!