Roll up named range estimates to parent records

I use named ranges for adding t-shirt size estimates to my epics. I want to roll these estimates up across epics to the associated initiative so I can easily understand the effort and costs of the full initiative. This roll-up works for other scenario types and this same behavior would be ideal. I do not need to aggregate the t-shirt size across all epics when rolling it up. Just rolling up the total hours up to the initiative is what I need to make reporting on initiative capacity data easy.