Do you even need to worry about indirect?
I just did 3 months and a random bunch of names in B5:B35
Code:
=SUMIF(Jan!B5:B9, "John", Jan!D5:D9)+SUMIF(Feb!B5:B9, "John", Feb!D5:D9)+SUMIF(Mar!B5:B9, "John", Mar!D5:D9)
Instead of the name in quotations you could point it to another cell that has the name you want to add to the total
Code:
=SUMIF(Jan!B5:B9, Summary!J1, Jan!D5:D9)