Here is a detailed description of how fee pooling works:
Essentially the only thing that matters is that the sum of all the fees of all the transactions in a group cover the required fee.
So if you have a group of two transactions (tx1,tx2):
either both tx1 and tx2 fees are at least 0.001
or tx1 fee is at least 0.002 (and tx2 fee may be 0)
or tx2 fee is at least 0.002 (and tx1 fee may be 0)