Using a date index within a SUMIF for prior date

[HM_23]

Right now the SUMIF formula gets the date from a specific cell but I would like it to come from a column of dates where it recognizes week prior. This data comes through each week, but I'd like the formula to point at the week prior (and if there's a way to make the index update automatically with the new prior week each data load, that would be awesome).

[#2]

@HM_23 

Your description is a bit ambiguous. "Week prior"--prior to what? Current week? Current week beginning with Sunday, Monday?

A series of "prior weeks" drawn from a column (you do suggest that possibility with this wording, " I would like it to come from a column of dates where it recognizes week prior")

Can you post a copy of the file (after first taking out any names or other potential-privacy-problem data) on OneDrive or GoogleDrive, and paste a link here that grants edit access. But also, please, clarify what you want done.

If you prefer to figure it out yourself, here's a link to a comprehensive list of Date Functions.