Can I have one section of a formula check two different sheets?

Jerexify

So, here's what I'm trying to do. I have three sheets in total I'm working with.

All three sheets contain a unique identifying number for easy reference.

Sheet A = Master sheet which is where the formula is housed.
Sheet B = Sheet with usage data for site 1.
Sheet C = Sheet with usage data for site 2.
Both Sheet B and Sheet C have all the same items, but their usage data is different based on a different viewpoint. Think articles on websites, where one sheet shows how many times the article was accessed from the first website, and the second sheet shows how many times that same article was accessed from a different website.

Essentially, is there a way to write a formula that says to check sheet 1 to see if the usage, based on the unique ID, is greater than 0. If it is, then I would like it to pull that number into the cell. If the usage is 0, I would then like it to check sheet 2. If the usage on sheet 2 is greater than 0, I would like it to pull that number. If the usage on both sheets is 0, I would like it to return 0. If the usage on both sheets is greater than 0, I would like it to return the sum of both numbers.

Is this even possible?

Thank you in advance.

Paul Newcome

You would use two SUMIFS and add them together.

=SUMIFS({Sheet B Usage}, {Sheet B ID}, ID@row) + SUMIFS({Sheet C Usage}, {Sheet C ID}, ID@row)